2003 engine stutters and or stalls on hwy.

[gregguy]

hello, my 03 windstar has a jerking or stutter at hwy speeds. Sometimes it will stall while doing 60-70 mph, It will not start in neutral, have to do a complete stop in order to reststart motor. This is dangerous stalling on hwy's with no shoulder to stop on. I have changed a blocked fuel filter and though it runs better, hwy stalling still occurs. When jerking happens, if i let off gas quickly, sometimes prevents the stalling. This has me worried for my safety. Any ideas would be much appreciated. p,s, codes 171,174 are on, but think tsb 13-6-1 would fix that. thx.

[wiswind]

There are a LOT of things that can cause this.
You should be able to start the vehicle in neutral.......which makes me wonder about the Neutral Safety Switch (AKA Transmission Range Sensor).

Check for any signs of a vaccum line being off.....
Super check the hose from the PCV valve to the intake manifold.....years of exposure to the oil vapors can soften that.
Also verify that the line from the flex hose to the rear valve cover (1999 and newer windstar) is intact.....if that is disconnected at either end....that is a huge vaccum leak.

Those are the cheap & easy things that come to mind.

If the stalling is only when you remove your foot from the accellerator, the most likely cause is the Idle Air Control valve (IAC).
There are posts on here as to how to clean it.
The IAC controls the engine speed when your foot is not on the accellerator.
There is a little motor that drives a shaft with threads on it (like a screw) that moves a valve open and closed.....and if it is sticking, then you will have stalling issues when your foot is not on the accellerator.

[gregguy]

Thanks for responding, no, stalling only happens when gas pedal is pushed. In fact sometimes when accerating off stop or light, motor stalls. also feels sluggish at hwy speed. I am wondering if the fuel pump might be going. Is there a way to test this while still parked. If its the fuel pump, will that not restart in neutral. think I heard something about ignition switch starts fuel pump. It really does feel like its sometimes starving for gas. thanks.

[danielsatur]

Air - Do a smoke test
Fuel - Do a fuel pressure test
Exhaust - Catalytic converter back pressure test

Does Heat play a factor?
Is the CEL on? yes

Fix the unmetered air leaks 1st

[12Ounce]

Fuel pump!