Car dieing when put under load

[Roger Heflin]

My car is dieing at idle when I put it under load (A4, put it in gear
or turn on A/C).   It just started this recently, and nothing has been
changed on the car in alsmost a year.  Once in a while it will die at
idel without a load, but I have stopped that by adjusting the throttle
set screw so it gets enough air to not die at idle.
 
Watching it in a scantool, the IAC will rise to a given number to
stabilize the idle, and stay there for 5-10 seconts, and then it will
rise to another number, and then stay there for a while, and it keeps
doing this until it hits the max IAC count (160), and which point in a
few seconds the engine rpm will decrease and the car will die.
 
The only thought I can come up with is that the IAC is no longer
working properly or dirty.  Last night I cleaned the IAC and
it still dies in a very similar manner.   Tonight I am going to watch
the scantool, and listen to teh TB whistle to attempt to verify the
IAC is functioning properly.  Anyone have any other ideas?
 
                        Roger
                        93 Z28, 123k