I have a goodman GMP100-4 furnace. It was shutting down after a few minutes. After a couple hours of trouble shooting I found excessive heat on the top of the furnace. It seemed that the top heat sensor was tripping. One of the wires that lead from the top sensor to one of the side sensor had taken a lot of heat and needed replaced. The furnace now runs but still gets too hot on the top of the case. Upon farther inspection I can see the last 2 gas nozels do not seem to be shooting flame through the "holes" into the "heat box"completely. I dismantled the nozel assy. Checked the nozels and tightened the gasket where the flame enters the heat exchange assy. The last 2 holes in the gasket show signs of heating up. I guess the question is.. What would stop the flame from completely entering the "heat box?

It sounds like your furnace is overfired or has a lack of sufficient return air or has discharge restrictions or has the wrong burner orifices or needs the gas pressures set with a manometer.

Sir you are playing with a device that really should be repaired by a professional OR at least a HVAC professional should do a ON Site inspection to find the real problem.