My '98 Lumina LTZ does not start when it's warm.
If I drive around long enough to get the engine hot, stop the engine,
then come back to start it 30-60 minutes later (while it's still warm)
it will not start. It turns and sounds as if it is going to start but
it does not catch.
If I come back to start it while it's still hot it will start.
If it is not starting and I pop the hood to help cool things it starts
once the temp gauge falls below normal.