89 5.8L rough ilde, dies. help!

hi guys. i just bought this bronco. 89 xlt 351. and i drove it home fine, changed oil and stuff. than i get home and do plugs and wires and flush and fill gas. (sitting for 5 years) i start it up to drive it around and it idles like garbage and wont stay running. ill give it some gas and it goes to about 2 grand than putts out and goes back to like 400 or whatever its at. is there like a checklist i could go through to see why it is doing this?

thanks in advance

nothing?

1) Exhaust. Check the fittings and the cat. (Start at the back, and work forward)
2) Electrical. check the sensors (including Throttle Position Sensor.)
3) Fuel. (Check the filters, pumps, and tank. Maybe disconnect the frontmost fuel line and have someone key it 'on' to see the condition of your fuel. Maybe the tank has inner rust and it's spitting in your line.)

cool. thank you

*update* i replaced the fuel filter. and i did it on the street. well it ran like crap still. would not stay running. i had to pump the pedal. but as i chugged up on the driveway. (incline) it started running fine. with almost perfect throttle response? so it seems to not want to run on any slope but incline???

*note to obvious* i DID put gas in it so the pickup line should be picking it up. but i only filled about 6 gal.

thanks again

Sounds like a definite cat problem. Let me guess that, if you approaching a hill, it would be rough at the bottom, smooth out some in the mid-grade, then bog down again at the top?

The catalytic converter chemically traps exhaust gas. At the end of their service life, the trapped gases prevent any new gases from going through the cat. When the engine is at idle, the clogged cat can choke the engine out. When you open th throttle, the new gases are going at a higher rate of speed, so they often push through the clog, only to clog up again once you lay off the pedal. An 89 is two years too young to be free of polution controls, so you would have to replace the cat to be legal. (You could remove the cat, but that's not legal....my state has it at about a $10K fine to run a vehicle without one.)

so a cat would really affect its idle depending on a slope? never heard of that.
also if im on flat surface. little pops come out of the intake when i give it throttle

there would be no way of me chekcing the cat unless i cut it because its welded on.

It wouldn't affect the idle based on the slope, more on the amount of throttle you give it. Low throttle=poor running, mid-throttle=about right, full-throttle=back to bad running. Is it welded on on top of the bolts that hold it on front, and whatever holds it on the back? Tap it with a hammer and see if you get a solid sound, or a hollow one.

yea pretty much my exhaust is all welded up to the muffler. but the cat is the first champer than the resonator than the muffler?

yea ill hit it with a hammer. than probably drill some big 1/2 holes just to get some air flow so i can get to a muffler shop.

yea pretty much my exhaust is all welded up to the muffler. but the cat is the first champer than the resonator than the muffler?

yea ill hit it with a hammer. than probably drill some big 1/2 holes just to get some air flow so i can get to a muffler shop.

Did that do the trick i have the same problem

This vehicle has two pumps one in the tank and one back by the tank,the little pump in the tank primes the big pump. The fuel filter is by the big pump with a cover over it. To check the small pump disconnect the fuel line before the big pump and hold a coffee can under it have somebody try to start the vehicle. It only pumps 3 or 4 psi if no fuel replace. If you ever tried to prime a well pump you will understand. If the big pump looses prime you are having a problem.
They have a fuel pressure regulator by the fuel rail unplug the vacuum if it leaks replace. You should check with a gage but if it runs better with the return line pinched off in a rubber hose section replace the regulator.

I know this is an older post, but I'll reply to it anyway. I had the exact same problem,, Truck ran fine,, Did a tune up for the hell of it, wouldn't idle afterwards. After many hours of cussing and throwing stuff, Someone told me that they knew what kind of plugs I had put in the truck just by the way it was running.. And they were right.. I went cheap on plugs,, yup, I put champions in a Ford..Champions only do well in Dodges and "other" yard equipment. I got rid of the Champions and my problems went away. I have seen countless others since then, And hope to see no more,,