Even though the problem is related to a 1997 Lumina Sedan, I am going to post the issue here, as it may be a more general technical issue.

My Lumina is 1997 with the standard 3.1 V6, it has never given me any problems until recently, when it did not want to start up. The fuelpump and the external filter were replaced and it would start up somewhat better again, however not as "before". Then they replace the camshaft sensor because of an intermittent code, checked the spark plug wires and exchanged all 6 Plugs with Platinum plugs.
The MAF-sensor had been changed about a year ago because of a code as well.

Now, what it is (still) doing are these things:

1. When it is cold, it starts as always before, however
2. When the engine is hot after a longer drive, it barely starts up, idles very rough and you may hear misfiring all the way to the back (muffler). If you press down the gas pedal, the condition becomes worse, the engine stalls and finally dies. Once it has cooled down 30-40 minutes later, it starts fine and you can drive it with no issues. This problem can be triggered and repeated by driving it for a while.
Please note, the engine will restart for about 5-10 minutes after you shut it off after a longer ride. 15 minutes later it will start rough, idle rough and finally dies, as described above.

3. I tried a higher speed in an open safe area once, and I felt a minimal but noticable loss of power at the "higher end" of the speedometer, the Service Engine Soon Light came and blinked, but when reducing speed again it went off again and stayed off!
No codes have been set so far, NO codes have been permanently being stored at this time!

If anyone has a hot idea what else to look for, please let me know, this is an odd issue and probably the underlying problem will be hard to diagnose because the problem is only there once the engine is hot, while there are absolutely no codes!

Best Regards,
Klaus