My son did some research, based on the symptoms, and his diagnosis is: Either a fuel pressure regulator or a spark plug. I had a spark plug do this once before but it was because the distributor wire wasn’t tight. Burned the wire and I had to have the distributor replaced.
So at least the problem is being narrowed down. If I can just get my SiL here to actually LOOK at it, I’ll be good!
The fuel pressure reg seems more likely.
A spark plug, if only one, would just make it miss like a bucking bronco on three legs (it's a four cylinder. Three legs.. Sorry, bad yolk. ;-) If a general ignition problem such as bad coil or whatever that year Geo used (don't know if they were into the integrated electronica in 1992) you would think that it would also act up when it was cold, not exclusively when it was hot.
You really need someone to stick their head under the hood. But you knew that. My beam-me-up-Scottie-device hasn't worked for years, else I could just drop into your parking lot..