I have a 96 F250 with the 5.8 EFI V8 that had the same problem. The Idle Air Control Valve was replaced and all was fine. The IACV is a computer-controlled air bypass valve located in the throttle body. It helps control idle speeds by allowing air to bypass the throttle plates as to increase the idle speed.

-cheers

 

Today replaced the idle air control valve, spark plugs, Air change temp sensor. Still the same thing. Will check egr valve and the fuel pressure regulator tomorrow. Any other ideas?

 

If its not leaking fuel from the FPR and you have good pressure on the rail I would be looking toward the cats. a clogged or haft clogged cat wont allow the exhaust out into stalling the engine. When holding the RPMs up you have more exhaust pressure to force it threw. With no codes thats really your last to options and sence it has been getting worse slowly Im thinking cats.

 

Does it matter if its an after market cat? Its not really that old 5 yrs tops. I'll check fuel psi tomorrow along with the fpr.

 

I do not think a Cat will cause it not to start when it is cold.
I would trace the ECT and ACT wires back to the computer and see if there are any breaks and the pins are OK at the computer plug.

 

He also stated he could get it started pending he held the idle up to keep it running. Has this changed?

From my experience aftermarket cats. ussually dont last as long as stock could try discounting the exhaust before the cat and see if it will run correct or not.

 

When i go out to truck it fires right up and about the time the idle drops back down (3 seconds) and starts running rough. Engine is shaking all over the place. If i hold it about 2-3 thousand rpms its alot smoother. As soon as i leave off the gas it spits and sputters and shuts off. To get it running again right away i have to hold it to the floor and you can tell its flooded.

 

The only problem is that the shop that did the exghust welded everything together. Guess i have to cut it to see if its the problem or not.

 

I had a dumb moment in think the cats. I forgot it was flooding out. If I am remebering correctly the only sensors that effect the amount of fuel the ECU injects would be the ECT,IAT,O2 and the MAP Sensors. If you are not seeing codes I would haft to say the MAP sensor is the only thing left that would cause it to flood out enless there is a problem with your wiring or your ECU. The TPS could also be reading that the throttle is open father than it is but ussually they fail in the closed postion. Is it still a cold only problem or is it a constant issue now?

 

Its mostly to cold here right now to determine if its still only the cold issue or not. Doesn't getting alot of raw un-burnt fuel in ther exghust hurt the cat? I'm going to check the fuel regulator tomorrow after work. I did pull off the vacuum line once but never cycled the key. It had no sign of liquid in it.

 

Yes Unburnt fuel will damage the converter to a point but thats not normally the cause of a clog. At least not in a 5 year period. (my opnion) To me I dont think it has anything to do with a fuel leak your getting fuel obviously if you can smell fuel and it runs at higher RPMs if you were loosing fuel threw the regulator it would cause it to loose power in the higher RPMs because of the need for more fuel, leak equals less fuel. If you have a AMP/Volt/ Omz meter you may want to test the TPS. The MAP sensor is a frequncy so Im not sure how to test this. If the TPS tests good Id lean to the MAP if the TPS tests bad replace the TPS. How to test can be found here for the TPS-http://www.fordfuelinjection.com/?p=30

The only reason it should be flooding itself out is something is telling the ECU to dump more fuel than needed. In my opinion all your symtoms point to to much fuel at idle. IE a bad sensor that involves the air or throttle readings.

 

Checked a bunch of stuff today. A guy told me to pull the vac line off the egr valve. Pulled it off and the damn thing purrs like a kitten. put the vac line on and bam right back to shutting off. Going to parts store to get a new one.

 

Glad you found the problem. I was under the impression you had already done that.

 

I do not think the EGR valve is your problem. Your problem is the EGR solenoid (EVR).

 

Of coarse put the new valve on and same thing. As long as vacuum line off it runs, but once you put it on it shuts off. What and weres the egr solenoid? Will it hurt anything just to run this off with a screw in it?