so a could days ago my truck started acting funny. most of the time....she wont hold an idle. even when the motor is warm she wont, she will crank but wont idle, and if for some reason she does idle its at like 400rpms. when I come to a stop she dies.

01 5.4. stock everything, not tuned and my only step is to take it to the shop cuz Im out of ideas. yall got any?



oh and to go I have to crank it, pump the gas a lil and get it up to where it normally does with my foot and put my other foot on the brake and put it in drive and im off. i hate it.

 

Is the CEL on? Have you had the OBD2 scanned for codes?

It's probably a bad IAC.

 

I had my edge scan thru for codes and it did come up with one, something about valve timing, but it went away....

 

What was the number of the code? If it didn't start with "P", ignore it.

 

I had a similar problem and it turned out that one of the vacuum hoses had become detached. It ran fine after re-attaching.

 

Yes, and that should trip a CEL and throw a P0171 and P0174.

 

Mine did the same thing it was the Idle air sensor valve...pretty sure that what it was called.
it looked liked a vacuum canister next to the throtle body

 

^ ya it was the idler control module, just behind the TB. got er fixed up and runs great now.