My car goes below 500 RPMs and sometimes stalls when braking and almost to complete stop. I replaced the IAC last night, I have no vacuum leaks and the whole vacuum tube system was just replaced, I have brand new fuel injectors. I have headers, no cat, and welded an 02 sensor in to the headers... Is it the MAF? TPS? Any ideas will be appreciated.

 

Backprobe the MAF connector "C" and "D" terminals, start the engine, and read the DC voltage at idle.

 

How many inches of vacuum are you reading on the gauge? You should have at least 20 inches. Does the needle fluctuate at all? I just had this same issue. I had replaced the head gaskets and I had one valve adjusted with too much lash taken out. The valve was constantly hanging open. So it was always idling like crap and trying to die. It ran better at high speed. But once I fixed the lash on the valve, she ran as smooth as silk.

 

My valves should be fine, I thoroughly cleaned and serviced my heads and valves recently. I'm not quite experienced enough to test the MAF but I did clean it. I am installing a throttle position sensor in the morning and after doing extensive research, I am almost positive that this will be my fix. I'll let you guys know. Thank you for the input.