I have a 1997 base model with a 2.7L engine. With the a/c off, my tach reads a steady 700. If I turn the a/c on, the tach goes up to 900, but after a few minutes, the engine runs rough and the rpms drop to about 700 - 500. Sounds like it is going to stall, but then it shoots up to 900 again.

I very recently installed new plugs and wires, remanufactured alternator and cleaned the MAF.

Also, today I used Rislone "Fuel, Exhaust and Emissions System Cleaner" just to complicate things. LOL. My catalytic converter tends to occasionally throw P0420 from time to time. I have used the Rislone product with great success in the past, and I occasionally use it to try to stay ahead of that problem.

I suspect the IAC and throttle body need a good cleaning, but I thought I'd ask for opinions first.