Lack of power problem with 92 K1500

I have a 92 K1500 with 210,000 miles on it. It also has the 5.0 L in it so the power is already a little lacking haha. But really it has trouble getting up to highway speeds. It lacks power bad!!!! I had 285 tires on it and couldnt get it to go faster than 55 in OD with cruise control set, with out constantly down shifting. It now has 235s on it and it still is way under powered. At 75 mph it downshifts quite a bit more than it should. On any small hill at all it will downshift like crazy. I had a buddy that had a lifted k1500 with as many miles as mine and had a 5.0 L in it too and he was running 35's on it and the truck had no problem turning them. So I know my truck lacks alot of power that it normally shouldnt.

The truck does fine at lower speeds....other than right around 20 -30 mph it like "bogs down" I guess would be the right way to put it. Other than bogging down it also stutters when you let off the gas pedal at that speed. The engine stutters a few times then goes back to idling normally. I thought all this problem might be due to the fuel system so I completly rebuilt the tbi and cleaned it and all the sensors, as well as installed a new fuel pressure regulator and fuel pump. I was hoping that would fix my problems. Well it didnt really do anything. It idles a little smoother but other than that it did nothing for my problem.

My next thing im going to try is the catylatic converters. I believe they are plugged(got them off another pickup because I had to completely rebuild my exhuast) The reason I think it is the cats is because a while back I had my exhaust flange donuts wear out on both sides. The pickup ran a lil better then but not like it should still. Since I replaced those gaskets though, at high rmps the engine like misses and stutters before it shifts. So I am thinking the cats are plugged. It could be none of the above and something I havent thought of yet. Thats why I am coming here to see what you guys think. Thanks for the help in advance

I have a 92 K1500 with 210,000 miles on it. It also has the 5.0 L in it so the power is already a little lacking haha. But really it has trouble getting up to highway speeds. It lacks power bad!!!! I had 285 tires on it and couldnt get it to go faster than 55 in OD with cruise control set, with out constantly down shifting. It now has 235s on it and it still is way under powered. At 75 mph it downshifts quite a bit more than it should. On any small hill at all it will downshift like crazy. I had a buddy that had a lifted k1500 with as many miles as mine and had a 5.0 L in it too and he was running 35's on it and the truck had no problem turning them. So I know my truck lacks alot of power that it normally shouldnt.

The truck does fine at lower speeds....other than right around 20 -30 mph it like "bogs down" I guess would be the right way to put it. Other than bogging down it also stutters when you let off the gas pedal at that speed. The engine stutters a few times then goes back to idling normally. I thought all this problem might be due to the fuel system so I completly rebuilt the tbi and cleaned it and all the sensors, as well as installed a new fuel pressure regulator and fuel pump. I was hoping that would fix my problems. Well it didnt really do anything. It idles a little smoother but other than that it did nothing for my problem.

My next thing im going to try is the catylatic converters. I believe they are plugged(got them off another pickup because I had to completely rebuild my exhaust) The reason I think it is the cats is because a while back I had my exhaust flange donuts wear out on both sides. The pickup ran a lil better then but not like it should still. Since I replaced those gaskets though, at high rmps the engine like misses and stutters before it shifts. So I am thinking the cats are plugged. It could be none of the above and something I havent thought of yet. Thats why I am coming here to see what you guys think. Thanks for the help in advance
Taller tires and 5L engine and high geared rear end and poor tune up = NO POWER!!!!!!!!!!!!

What is your gear ratio on rear end and what was you Buddie's gears?

Why not do some proper testing and and a good AC delco tune up first before throwing more parts at it?

A vacuum gauge will tell you if exhaust is plugged and how engine is running.
Hook up gauge and give us your engine vacuum readings at idle and at 2K rpm.
Also tell us if gauge needle is fluctuating?

A tune up has already been done, I bought the pickup and from where I work(I work on a farm/feedlot as a mechanic) When I bought it I did a complete tune up on it besides the fuel pump and throttle body. Which as you know I just did that. The only thing as far as tune up goes that I didnt replace were the coils and the distributor. Other than that everything else has right around 10k miles on it. I am not sure what gear ratio my buddies pickup has but mine has 3.73 gears on it. I am pretty sure its not just something a tune up can fix and its not due to gear ratio, I know that because there has been times when it has ran like a bat out of hell and other times that it has ran good but not right. Now it just has no power at all everytime I drive it the power is about the same or lack there of power.

I havent done a vacum test on it and I am not to concerned with doing one. The cats that are currently on it are going away one way or another so if they are plugged great if they arent they are still coming off and new ones are getting put on because I am completely re doing my exhaust. On that note would the fact that it has a Y pipe off of a 1996 K1500 make any difference? I know my pickup originally only had one cat, where the 1996 Y pipe thats on my pickup now has 2 cats, one on each side.(thats why I am re doing exhaust. Im putting it back to "stock" by having only one cat, but I am putting glass packs on it instead of stock muffler)

A tune up has already been done, I bought the pickup and from where I work(I work on a farm/feedlot as a mechanic) When I bought it I did a complete tune up on it besides the fuel pump and throttle body. Which as you know I just did that. The only thing as far as tune up goes that I didnt replace were the coils and the distributor. Other than that everything else has right around 10k miles on it. I am not sure what gear ratio my buddies pickup has but mine has 3.73 gears on it. I am pretty sure its not just something a tune up can fix and its not due to gear ratio, I know that because there has been times when it has ran like a bat out of hell and other times that it has ran good but not right. Now it just has no power at all everytime I drive it the power is about the same or lack there of power.

I havent done a vacum test on it and I am not to concerned with doing one. The cats that are currently on it are going away one way or another so if they are plugged great if they arent they are still coming off and new ones are getting put on because I am completely re doing my exhaust. On that note would the fact that it has a Y pipe off of a 1996 K1500 make any difference? I know my pickup originally only had one cat, where the 1996 Y pipe thats on my pickup now has 2 cats, one on each side.(thats why I am re doing exhaust. Im putting it back to "stock" by having only one cat, but I am putting glass packs on it instead of stock muffler)

Well if you do not want to do a simple vacuum test that would tell you if you have a engine running problem or plugged exhaust.
You are just wasting our time trying to help you.

JUST KEEP ON THROWING PARTS AT IT.
Until you run out of money or get luckie and hit the right spot
GOOD lUCK

Its not that I dont wanna do a vacuum test, Its I dont have a vacuum gauge first of all, and second of all where I live/work is literally out in the middle of no where. I work 6 days a week and out here on sundays all the bussinesses are closed because its just a small town. So i have no way of getting one besides ordering it offline. And I have went down that road before buying diagnostic tools to figure out whats wrong, the diagnostic tools shows that that isnt my problem and then basically I have a tool I used once and will rarely if ever use again. At least if I am replacing parts im putting stuff into my pickup that will eventually go bad or wear out. Granted it may not be bad when I put the new stuff in, but eventually it will go bad so at least im not wasting my money completely.

Its not that I dont wanna do a vacuum test, Its I dont have a vacuum gauge first of all, and second of all where I live/work is literally out in the middle of no where. I work 6 days a week and out here on sundays all the bussinesses are closed because its just a small town. So i have no way of getting one besides ordering it offline. And I have went down that road before buying diagnostic tools to figure out whats wrong, the diagnostic tools shows that that isnt my problem and then basically I have a tool I used once and will rarely if ever use again. At least if I am replacing parts im putting stuff into my pickup that will eventually go bad or wear out. Granted it may not be bad when I put the new stuff in, but eventually it will go bad so at least im not wasting my money completely.

reading all this you are so cheap you are loosing money not saving.

tools are needed to repair and properly trouble shoot any piece of equipment. having the repair manual also is needed. If you lived in antactica I can understand the issues with getting tools for correct repair testing. colorado is not a remote isolated state.

vacuum gauge is a low cost item. this can be used to determine more than a restricted exhaust ! somewhere on this forum I posted vavuum engine troubleshooting this explains all of what can be had from a 20 buck cheapo vac guage ...

I did what mt 2500 said 2 weeks ago throw money at it and maybe I get lucky ..........I WAS IN LAS VEGAS !!!