Hello to anyone reading, I am new to this so forgive me if I am ignorant to how things work here. I have been having this issue with my truck for a little while now. It is a 1988 f250 4x4 351w efi C6. The truck will start and idle just fine. If I let it sit for a few days it may die after about 30 seconds of idling but start right back up and idle nicely. Once it gets up to temperature it will bog down as soon as I try to give it gas and die out if I give it too much gas. It also seems like it may be overheating slightly when this happens. I check codes with the engine off. All i get is 81 & 84 for koeo and 33 & 96 for cm. (EGR has been deleted along with TAD/TAB) I haven't done koer codes. Just wondering if anyone else has had this problem and can point me in the right direction. Don't wanna just throw parts at it until I finally figure it out and I can not get it to a shop to be looked at. Any insight would be super helpful and greatly appreciated

 

You saved yourself a bunch of money and time by not throwing low quality new parts at it. You can probably diagnose this problem with a harbor freight multimeter or a fuel pressure gauge. This problem has come up multiple times in the recent past and you can search for it using the 'search->advanced' tool at the top of the 1987-1996 forum. I don't remember how the last few were repaired.
you've already checked for codes! Congrats! You've completed the first step. Next thing to do is check fuel pressure. The 3 big auto parts stores loan out fuel pressure testers for free. Screw the gauge onto the test port on the front of the fuel rail. Then turn on and off the ignition about 3 times without starting the truck to prime your fuel system. After a few key cycles, the fuel pressure psi will stop increasing.
Record the engine-off psi reading. Should be 35-45
Then start the truck and let it idle for a minute.
Record the idle psi reading. Should be 30-45
And then, tape the gauge where you can read it from the driver seat and power-brake the engine with WOT.
Record the WOT psi reading. Should be the same as the first test.
If you notice the psi sharply decreasing at WOT, that means you either have a plugged fuel filter (rare) or a dying fuel pump (common).
Let us know the results.
Happy hunting.

 

Thanks for the quick response! I have noticed the fuel pump is louder than normal. And what I mean by that is I can hear it humming when the truck is idling. It's always done that but seemed to get louder. The pump came out of the junkyard 2 years ago and I have not replaced the filter so they are suspect. I will check fuel pressure and post back once I get results.

 

So I finally fixed the issue. The fuel pump and filter were clogged because the sock filter came off the bottom of the fuel pump, causing it to suck in rust and debris. The fuel sending unit that I removed also came from a 92-96 truck and was junk. So I had to buy a new sending unit, and a high pressured inline pump. Because it previously ran only on the pump in the tank. After cleaning the tank, installing both pumps and the new filter, the truck ran great! But the high pressure must've made my old brittle fuel line crack and spring a leak in between the filter and regulator! I made a trip to my local wreck yard and got some good fuel lines. All is well. I am by no means an expert but it seems to me that the sock filter coming off was my downfall. It was a fiasco going through the entire fuel system but at least I know everything is in good shape.

 

Congrats. Another problem solved.