won't go over 2000rpm

I have a 97 GMC Jimmy. In drive it has no power and it won't go above 2000rpm (sometimes on a good day it'll go to 2500rpm). I changed the fuel filter just to see if it would make a difference and it didn't. I changed the fluid in the transmission and it didn't change anything either. Spark plugs were changed about a month before it started doing this. I changed the egr and it helped ever so slightly at first ( it had more power and would go to about 3200rpm ) but after a day or two it went back to the same problem. One day I left egr unplugged and it seemed to run slightly better than normal so I've left it unplugged. My theory is a plugged CAT or muffler. Whoever owned the vehicle before me was a dumba** and had a security system hooked, problem with that is that he used the OBD2 port wires to do this. I've had it for almost a year and that hasn't effected anything though. Any suggestions anyone?

A quick test for restricted exhaust system is a engine vacuum gauge reading at idel and at 2K RPM.
If 2K rpm reading drops down or below idel reading you have a restricted exhaust system.
I would also run a fuel pressure check on it.
The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot or low on power fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

So most likely is a clogged CAT or fuel delivery issue. That's where I was looking already I'll just have to rent a a vacuum gauge and a fuel pressure tester and see where I stand from there. Any thoughts on some out of the ordinary issues? In case those 2 end up not being the issue?

We can not read the cars mind over the moniter tube.
You will have to do the.
PROPER TESTING TO FIND THE PROBLEM.
I did not say that was the problem just pointing you to proper test.
Post back vacuum and fuel pressure readings.

A vacuum gauge is a cheap tool.
Best to by one over renting.
It can be used many times for checking running.
And if installed in car it can be used as a gas saver to.
And pay for itself the first few hundred miles.
Good luck
MT

We can not read the cars mind over the moniter tube.
You will have to do the.
PROPER TESTING TO FIND THE PROBLEM.
I did not say that was the problem just pointing you to proper test.
Post back vacuum and fuel pressure readings.

A vacuum gauge is a cheap tool.
Best to by one over renting.
It can be used many times for checking running.
And if installed in car it can be used as a gas saver to.
And pay for itself the first few hundred miles.
Good luck
MT

Okay first off who is we? You're the only *** answering. Second I was just asking for other suggestions so I don't have to come back and talk with your *******. Third I think you mean BUY not BY and in the context used TO should be TOO. Get an education man. I know I can get answers from these items, but why do that when I thought intelligent mechanically inclined folk would answer my question without being a **** head.

If you want other ideas on it.
Start with washing your mouth out with a good bar of soap.
And Lose the attitude.
Good Luck
MT

Aisianbrother7,
MT-2500 is an extremely knowledgeable and experienced technician. He is very well respected on the forum, and was trying to assist you with your problem. Please read the forum rules that you agreed to with regard to respecting other members. If you cannot abide by the rules, you will be banned from using the forum.

MT. I want to apoligize for his rudeness. You are a great tech person and have helped me alot. Thanks and keep up the good work. Some people just want the easy fix and your telling him right. Some don't appreciate but others (myself) do.

who cares if you have a typo or two.......lol I bet your vehicles run better than any of ours.