Volvo Repair: Rough idle, air control valve, volvo 940

Question
In stop and go traffic, the engine on my  1993 Volvo 940 (not turbo) begins to run very rough after about 5 minutes or more and will kill unless I shift into neutral and raise RPM's over 2000. Also the A/C will not work below 2000 RPM's. Over this figure the car runs fine.

Thanks

Answer
Hello,
did you check the idle air control valve? Also, throttle may have problem. Please check them firstly.
And, may be AC pump (compressor) may have problem, because of this reason the AC does not work, and the car dies before 2000rpm. Try to check them. You can remove the V belt from the AC pump and alternator, and so you can try the car with battery power, we can understand thhat parts have problem or not...
Regards//Vedat...