I have a 2003 Mustang GT that stalls at certain times. However it only happens when my wife is in the car.
So if we are out for a lengthy drive and I engage the clutch, like when I’m at the top of a hill, the idle drops way down and the car stalls.
I cleaned the MAF wires and replaced the Idle air gizmo. This seemed to help but it still occurs occasionally. The car has 105,000 miles and the car idles fine.
Thanks for your suggestions.
Kevin
This is confusing. How did you get to the top of the hill without engaging the clutch? Engaging means the clutch is engaged, connected, the pedal is out.
I suspect you mean disengage.
Refraining from making smart remark 
You mean it only happens when there are two or more people in the car I presume. That’s possible, the heavier the load the more a minor engine symptom like that could show up. hmmm …
Beyond keeping routine engine maintenance on schedule and checking for diagnostic codes, suggest to start by comparing these against specs
Have you tried changing your fuel filter and spark plugs? EGR? Random issues are tough to sort out but starting simple and going from there never hurts. If you made some progress, keep going in that direction. Make sure you don’t have any trouble codes, good fuel pressure, and good coil packs. It might be a loose or corroded ground wire, make sure all your connections are good. Beyond that I’d start looking to sensors, crankshaft, o2, camshaft, tps, coolant and on down the line. I’d really lean towards electrical though if it’s that intermittent.