1993 Oldsmobile Cutlass Extreem low power in hot weather

The check engine light does not come on when I'm having the low power problem during warmup. It has come on occasionally when driving at highway speeds (70+) for more than 15-20 miles, and goes off as soon as I slow down. The engine seems to be running fine at that time.

I have not had the computer scanned. Is that something a dealer shop would do?

None of the parts stores in town have the ability to scan a computer older than '96 model. I called Hitek Repair and they will run a diagnostic for $89, but thought it should be done at a time that the problem is occuring, which probably means in the heat of next summer. It may be worth trying it now anyway. Any other ideas?

With the ignition switch on, but the engine not running, I shorted the right two pins of the top row of the Diagnostic connector. The Service Engine light flashed once, then twice, and repeted the patern 3 times. I would interpret this a a code 12. I also heard a sound like a small fan running while the pins were connected. Connecting other pin combinations did not have any effect.

I do not know the letter designations, but I jumped the last two terminals on the right hand end of the top row.

The catylatic converter has not been checked, but wouldn't a plugged converter cause performance problems all the time, not just during warm-up in hot weather?

Based on your suggestion of a temp sensor problem, I found and an article on the internet by Mark Davidson titled "Diagnosing Problems Related to the Coolent Temperature Sensor", and it makes sense to me. If on a very hot day, the sensor is telling the computer that the engine is warmed up when it really isn't, that could cause the engine to run very poorly until it actually does get warmed up. I don't even know where the temp sensor is located or if I would be up to changing it, but at least it gives me something to persue. Thanks for your help. I will post a donation.

It's the 3.3 v6. I looked and saw a 2-wire device screwed into the block just below the alternator, near where the upper radiator hose enters. It looks like it would be easy to change.