I have a 85 190e. The A/C comes on when ever it wants to. It doesn't run continously but will come on without a call for A/C. The push button controls don't seem to do anything as I have yet to turn on the A/C. Do I possibly have a bad control unit? Also after about 1/2 hour of driving, when I come to a stop, the car seems to idle below what it should and the oil gage will bounce a bit. I am worried that it will stall. When I put it in park it goes right to a smooth idle and the oil pressure stay even. Any thoughts would be greatly appreciated.

Thanks