Ok fellas,
We all know the drill... These 2004 5.4 engines are just plain ol' bad and with that being said my 2004 fx f150 with 177K miles is stalling(rpms bottom out) driving down the road and coming to a stop(coming to idle) and when trying to park. AND, its an intermittent problem.
Of course, not spitting any codes or CEL's. I've searched the site and there are multiple types of the same issues and solutions. Narrowed it down to either the dreaded vacuum line sandwiched against firewall and engine compartment, OR the cleaning of MAF, throttle body and IAC valve.
So, gonna attempt the cleaning and will report if this helps or hurts. Just curious as to whom else is experiencing these issues?
Thanks...

 

I'd start with cleaning the MAF and TB. Unless its a Heritage edition (old body style) it doesn't have an IAC. The 3 valve engine is drive by wire and the throttle motor controls the idle speed.

 

Stalling as described can also be cause by the torque converter failing to disengage if you have an automatic transmission (you didn't say).

Could be a vacuum leak, could be a gummed up throttle body or control, could be several other things.

 

There's a bad trip down memory lane....
Back in the 90's, GM had a RASH of this problem in their mid-size front wheel drive cars. I don't remember the trans. model, but the TCC solenoid would stick open and of course the car would stall as it approached a stop. Naturally by the time the tow truck brought it in, the sol. had cooled and resumed normal functioning (they almost always worked cold/failed hot). Then you got to watch and listen to the charades involved in trying to describe the problem, sometimes these were downright funny! Finally one day a guy described it as just like stopping a manual transmission without pushing in the clutch. I think I took him out to lunch.

 

I'd start by cleaning the IAC valve.

 

Where is he going to find it? See post # 2.

 

My guess would be right where the FSM says to disconnect it when removing the intake manifold...the passenger side of the engine.

 

That's the drawing for a 97-03 / '04 Heritage. There's no IAC on any 5.4 (3 valve) after that.

EDIT -- Actually I think that's a 4.6 motor, which is a 2 valve and does have an IAC.

 

Also, to the OP, if you're going to clean the TB I recommend removing it first. You'll be able to do a better job with less chemical and you're not putting all that crap through the cats. You'll also avoid the nearly inevitable check engine light that comes with cleaning it in place.

 

My '07 F150 would frequently stall at traffic lights or turning into a parking lot or road. It never threw any codes.


Last week, I replaced the FPDM (fuel pump driver module), so far, it seems O.K.


It's located above the spare tire, under the truck bed.


The problem could be a few other things; but that is something you could change-out, to see if it resolves it.

 

Fellas
Wow, thanks or all of the input, it always helps out a shade tree mechanic! Now, there are probably a zillion reasons as to why this occurring so Im going with the least invasive and the cleaning of the MAF and throttle body. Also, gonna remove it from vehicle and actually went out and bought, "throttle body," cleaner. Never knew there was a difference between that and carb cleaner.
Anywho... Gonna try it and again thank you fellas for all of the input!

 

I just had this same problem '04 F150 5.4
My truck threw 2 codes 1st O2 sensor replaced, no change.
2nd #6 coil replaced, no change.
Removed and cleaned throttle body and MAF sensor.
Truck runs nice and smooth, no more stalling. It idles in gear at a stop at about 525 rpm's. This seams low to me but from what I've read these trucks all idle around 500-600 rpm's.
I hope this works for you.
Please let us know your results.

 

Befor


After