Idle Speed Motor

My '90 T'Bird was accelerating without me putting my foot on the gas. Took it to the mechanic and he determined that it was the idle speed motor. Had it replaced and it seemed to have fixed that problem. Soon noticed that the car would shudder whenever you turned the air conditioner on - either on Max A/c or regular A/c. There now seemed to be no difference between them. Well today the A/C died - only blowing out warm air and it made a terrible noise. ( I had the idle motor put in about 1 month ago.) When it was possible for me to look at the car closer I realized that after I turned the car on and then pushed one of the A/C buttons - it kills the engine. Anybody have any idea what is causing the car to die and do you think that it has something to do with the original work I had done on the Idlespeed motor - since the A/C didn't seem right after that.

It sounds as if the AC compressor has seazed up,,try this,,,take off the belt then try to turn the A.C. clutch use a 5/16 wrench or socket and put it on the little bolt in the middle of A.C. clutch and try to turn it,,if no turn then the A.C. compressor has locked up and the motor is trying to dye because it is locked up,,,now did you retrofit your bird to 134a ??
the A.C. problem is just a coincedent I dont think there is a connection between the AIC replacement and the A.C.,,but normally the Ford A.C. units are a mother I have a 1989 supercoupe and I had mine lock up on me and I went to retrofit it to 134a and then found it had all the black carbon threw the hole system//man what a nightmere!! message me if you are locked up and I will help you do the transplant to 134A and tell you what you will go threw if you dont do it right,,and a garage will want your first born to replace it so best do it yourself..Talk to you soon Im sure lol.