I've got a 2004 with 5.4l engine, new body style . When the engine is still cold, It idles fine (750rpm) no stalling. I put it in reverse to back out of driveway-everything is still good- then I put it in drive and it dies-I can restart and put in drive and it goes. But it shifts 1,2,3, and I'm still only going 10mph and it's bogging down. If I start in D1 then shift D2 it's fine. Once the engine is warm it seems ok-no stalling or bogging down. I've replaced fuel filter, had throttle body and maf sensor cleaned. I bought a iac because reading various forums-It sounded like that could cause the problem-but I can't find the stinking iac on my truck. Napa gave me part #2-20269 Can anyone help?

 

Correct me if I'm wrong, but I don't think a fly by wire engine even HAS an IAC. Doesn't the PCM simply open the throttle plate a bit farther?

 

i don't know i can't afford anything that new

 

Maybe thats why I couldn't find it. Any idea's on what could be causing the problem.

 

Don't know if this will fully apply to you but I was having a similar issue a few weeks ago. My 05 5.4L would do it when shifting between R and D for parking and things like that, hot or not. The problem for me progressed quickly. Turned out to be a bad fuel rail which kept flooding the injectors and plugs. If worst comes to it, go to an Advanced Auto or Autozone. Most of them have code readers and if your truck is recognizing the problem you should be able to correct it before it gets to the stage mine was. $1500 fix is a little rough on the wallet.

 

Checked with autozone for engine codes- none shown
Confirmed with ford - no iac valve for this year model truck
Idle reads about 600-700 when cold - is that low
Idle drops to about 400 when shifting from reverse to drive
Truck is 4x4 supercrew, new body style,5.4, with 48k miles-I bought used 2 weeks ago, as is
I would appreciate any troubleshooting advice.

 

First thing to check on used cars is the battery. I know its a stretch but I have bought alot of used cars.