Hey fellow f-150ers. I have a 95 f-150 ext cab 4x4 5.8. Every single time i start truck, idle goes up to about 1100 rpm(normal) then about 10-20 seconds idle kicks down to about 900rpm then 10-20 seconds later truck starts loping idle kicks down to about 500-400 rpm and wants to die but i have to tap gas pedal to keep running and i do this for about 5 minutes and then it clears up and runs fine. Even during driving everything is fine, only does this on start up and it dont matter when i start it, i can drive for 1 hour shut it down start it up and same thing. Or i can start it and run for 20 minutes and kill it and start it up and do the same thing.Outside temp doesnt matter either.has been doing this for about 3 months now and check engine light does not come on at all, except when turn key like normal. Please any help???

 

have you read the codes yet. if so what codes are you getting. the check engine light doesn't need to come on for it to store codes.

 

have not read codes yet work in a shop and everyone knows that codes dont always tell you what to replace to fix the problems and do you think i can get anyone to pull codes for me?? Heck no.just thought somebody might have had same problem before?

 

it kind of sounds like a problem with the throttle pos. sensor but it is hard to say with out the codes. you might try pulling it and cleaning it. it is very easy and a good place to start. also check all vacuum hoses and jiggle test the wire connections.

 

replaced tps last fall, replaced IAC valve 2 days ago.

 

Codes NEVER tell you to replace ANYTHING. They tell you where to START your diagnosis.Why do you need someone else to do it? Don't you have access to a paperclip? Read this thread. You can skip to the colored text & links if it's too boring to read the whole thing, but read my last post in it.

The high idle sounds like a vacuum leak, but the loping/stalling means it can't be. Together, they suggest a bad IAC, but that's not likely if you bought a Ford one. Since it happens even after the engine is warmed up, it's not likely the ACT or ECT, but it could be the TPS, or anything in the EGR or ignition systems, especially the SPOUT circuit. So read this caption:



Then get a Haynes manual & a multimeter, and start TESTING things - not replacing, until you find something that fails a test.

 

Replaced O2 sensor and fixed it!!!! its amazing that a 45$ part that took 10 min to install and i let it go for 3 months!!