I have a 1989 Buick Regal (that my father-in-law bought new) with the 3.1 L engine. It's a super beater car that runs great almost all the time, but when climbing a long grade in hot (>100 F) weather the engine dies. After a few minutes' wait it will restart and continue uphill for a couple more minutes before dying again. This process will keep repeating until the top of the hill. In less than 100 F weather, and without hills that climb thousands of feet, it runs great. The engine's dying seems to be related to external temperature as the engine/coolant doesn't overheat. I figured it must be the engine control computer, or something else not directly attached to the engine but exposed to ambient temperature in the engine compartment, crapping out so I replaced the computer but it didn't make any difference. The crank sensor doesn't seem a likely culprit since that's bolted directly to the engine block. Maybe the ignition module?

Have you ever run across anything like this, or do you have any thoughts as to what it might be?

Thanks in advance for any suggestions you might have.