94 7.5L EFI in an RV. Idles ok, but when I pull it into drive or reverse, it stalls. If you tap the throttle at the same time you can save it and it will calm back down to a decent Idle. When going from drive to park the engine seems to race a bit, but will again eventually settle down. I checked all the obvious stuff, vacuum leaks, electrical plugs and whatnot. Same thing cold or warm. I'm leaning towards IAC, but thought I'd query the crowd before I start buying parts.

 

Clean and reset the IAC first.

 

You checked all the obvious stuff?
Like codes?
A scan tool with some pid capability?
Make sure the TP pid is above .8v at idle, you could backprobe the sensor connector with a DVOM
Clean the throttle plate and the injectors?
The Maf sensor has a spider web in it?