[67 bird]

I have a 2001 mustang with a 5spd.

Only while driving does this happen. Won't do it while out of gear and sitting there even if you rev it up..

What happens is, Say you're coming to a stop at a light and you push the clutch in. The engine will rev to around 2000 rpm and slowly cycle back down to normal idle takes 5 to 10 seconds. You can bump the clutch and bring it back down right away.

I have read on other sites it may be the IAC or the 2nd switch on the clutch pedal. Any Ideas..

The Bullet has the answers I bet.

 

[longstroke]

I would guess IAC.

 

[67 bird]

Thanks Longstroke, but I want more opinions so here is another members wife (speedfab) LOL..

 

[BIGWHUP03]

I would guess if it goes away with the clutch pedal it would be that switch. I don't see how that would affect engine RPM though. Are you sure its not just coincidence?

 

[67 bird]

I tried all other ideas. Disconnected cruise control, made sure linkage was not binding, cleaned air filter (K&N). shut it off restarted it, clutch in, clutch out, revved it. only does it while moving.

After typing that I got an idea..The only thing I haven't tried is popping it out of gear while driving.

 

[BIGWHUP03]

Do you have aftermarket injectors? Another possibility could be the Fuel Rail Pressure Sensor. It makes my Cobra do all kinds of dumb shit like that.

 

[3barS197]

1st question:
is the car all stock?

If so, it is often times caused by filthy IAC and grimey throttle body blade.
A dirty MAF element will also cause similar issues (caused often times by oiled filters)..

The ECM looks at vehicle speed and Clutch position to control "dashpot", which is the rate at which the IAC return to "idle".
If the ECM has crappy input (such as a dirty maf) the IAC is forced to over compenate, causing a surge and stalling...
The same holds true if the IAC and throttlebody are crudded up, because the amount of airflow/duty cycle has changed.

 

[67 bird]

Yes all stock and it does have an "oiled" K&N filter.

 

[3barS197]

Remove the MAF from the air box, rinse the filament with a little carb/brake clean, reinstall.

The oil from the filter is often times pulled through the filter and deposited on the maf...

 

[NY Nova]

^^^^X2...this sounds very possible

 

[cornbread287]

A dirty throttle body or bad tps will cause this too. If the computer doesn't see the tps voltage go to closed throttle it will hold the iac open until the car comes to a complete stop.