Try data logging it and see what shows up

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Whoo I have this issue from time to time! Im not sure what is happening either. I figured I just needed a new tune but mine only happens when Im reving at a Camaro or something a stop lite. It will idle to the point of stall and catch itself (sometimes). Only when I rev very high will it do this which leads me to think a tune issue because the EEC cant adjust quick enough. Figure this one out my friend and Ill praise you. I cant afford a $400 tune on a hunch so let me know!:dunno

Oh and my car is way past for a tune like a few years past easy so it needs it anyway. Could be unrelated but I don't like to think so.

 

Ahhhhhh...misery indeed loves company!

This problem just appeared out of nowhere (last year) after never having a problem since buying the car in 2007. When the problem does occur, it's sporadic, which means I'll be lucky if the car acts up while a Ford service tech is with me. Of course, even after returning back to the stock tune, the problem still remained. I will keep you posted of any new developments.

 

Mine does it too. I was told it was cuz I put a CAI on and didnt have it tuned, then I learned Mach 's dont need a tune for bolt ons..... So IDK. it scared the crap out of me one time cuz I was WOT on along turn and it shut off when I put the clutch in. The battery light went on until I turned the key and re-started it.

 

I went to the Ford dealer today and it was symptomatic for the Ford tech who rode with me on the first test drive. When we got back, he hooked up one of his scanning data tools to the PCM and there were no trouble codes of any kind. So then he cleared all the historical adaptive learning data from the PCM. He said it was more thorough of a "data clearing process" than just disconnecting your battery for an hour and reconnecting it. Then with the car running (and AC on), we went for a second test drive and my symptoms were not there. I then turned off the AC on the ride back to the dealership, and the symptoms it showed were different than before - the tach would drop down to 3 or 400RPM when coasting but then go right back to correct idle speed of 750/800RPM - no more needle hunting/wandering for correct idle. He told me to continue to drive it as normal and report back to him if I need to.

 

I was a tech at a ford dealer about a year ago and assumed he grabbed what is called a IDSD if memory serves and was data logging when you drove. I don't think we have the same issue but none the less you got it (fingers crossed)

 

Thanks - my fingers are crossed too - any new developments I will let you know. I hope you get your issue resolved as well.

 

(8) days later since visiting the Ford dealer and the car still runs perfect - no more stalling, idles from 1100RPM back to 800RPM when coming to a complete stop - I'm gonna quite pondering what caused the problem and keep enjoying the ride!

 

I have the same issue and its very common for mach 1. Its usually related to having an aftermarket CAI that doesn't use a screen. Its most commonly found with K&N while most people find C&L and JLT don't usually have the problem. Its something related to air turbulence entering the intake from the shaker and the affect it has on the mass air flow sensor from what I've found. Best you can do, which is what I do is, stay in gear and slow down to below 30mph ( where air is not a big factor) and then proceed to down shift and or disengage your clutch. This is the best way to avoid the stalling. Oddly enough our cars also sometimes develop a hanging idle due to the IAC design.