All of a sudden, my 93 245 won't idle. Before it dies, it surges up and down a bit. It also has a miss at cruising speed. If I engage the A/C, it will idle, but just barely. I know the ECU sends a signal to the idle air control valve to open it up a bit more when the A/C is activated, so I'm guessing the IAC is at least partially working. I've been all through this engine looking for faults, vacuum leaks, etc. to no avail. I replace the igition system, and the O2 sensor as they needed it for routine manitenance anyway. I followed the testing procedure in Bentley for the IAC (resistance check between terminals) and it's OK. I took it out and cleaned it, and put 12V to the terminals and the valve opens. The only thing I can figure is the IAC valve is bad anyway. Before I go out and spend alot for this thing, can anyone tell me if there is a definintive test? Also, could a defective IAC cause a miss when cruising at a constant speed? Thanks.