Hi, I have 1997 f150 4x4 4.6l, the truck stall on every light or slow traffic, when you put some gas you can see the revs go up and then go so down the engine stall, it start normally after , and if you put a lot of gas the truck go ok, on highway speed no problem , any idea , I just change oil, air filter , transmission oil, tomorrow I will try the spark plugs , but I think is more like idle valve, or someting like that

 

Could be something like a vacuum leak, bad or clogged EGR or PCV, or maybe a bad fuel filter not allowing steady gas flow at idle.

 

Idle speed is controlled by the vehicles computor or PCM. It does this electronically via the idle air control or IAC. As stated by prior post vacuum leaks can cause havoc while the engine is trying to idle. Has there been any check engine light (CEL) activity? A slow to close EGR valve can cause stalling when stopping, an open EGR valve is just another huge vacuum leak or more commonly called an intake leak.

 

I had the same problem as the OP, i changed the egr (valve and sensor) , pcv, iac, and the problem is still there. Now its worse when i come to a stop it idles really rough and low rpm, slam on the brakes and the idle isnt so bad.Almost like when i barely hit the brake it acts up, acceleration is fine. New plugs/wires less than 6 months ago, fuel filter less than 2 months ago, oil change 2 months ago. any ideas?

 

A clogged or bad IAC valve will cause the engine to die at idle. It can sometimes be cleaned but usally requires replacement.

 

I have over 146k on the original IAC. Take it out and clean it with carb cleaner. Be careful with the gasket as you may tear it. If you do, do not panic. Get a cereal box and trace the pattern on to the cardboard and cut it out. Instant gasket.

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The problem isnt always there just kind of shows up sometimes...i've replaced/ checked most of the emissions system now i'm wondering if its a transmission solenoid going bad, its the next logical awnser... i think. Possibly preventing the torque converter from totally disengaging? anyways i appreciate you guys taking the time help me get this fixed..

this might be a loooong shot but does has anyone every run those bosch e3's in their truck? I changed spark plugs to those about 6-8 months ago but, this just started happening. thanks again