My '93 recently started stumbling off the line and sometimes will try and die while sitting at a light. Seems to happen more often on hotter days when the car has been sitting. Drives just fine to work in the morning and then has problems usually at lunch and on the way home. No vacuum leaks as I just hooked it up to a gauge and didn't see any surging. Plugs and wires were done recently. Fuel pressure is unknown. I can also feel it very slightly stumbling at constant speed while cruising on the highway but it could just be my mind playing tricks on me. MAF sensor was replaced when I got the car as it was bad and then replaced again with a nicer sensor but I'm still willing to accept that it may be down to the MAF sensor being bad as I've heard finding a good one these days is next to impossible.

Possible Problem Causes I'm leaning towards:

MAF sensor fubared.
Fuel pressure problems.
Coil-Pack problems.

It only seems to happen under load and simply revving the engine while stopped elicits no stumbling.

On an unrelated note I noticed that my AC compressor will cycle on/off while the motor is running even when no AC setting is selected... Is there a way to make it stop doing that?

Thanks everyone!