Engine not starting

why does my engine not start when brought up to operating temperature? It will turn over but not start. If you let it set for approxamately 4 or 5 hours, it MAY start. When you drive it to operating temperature and stop to put it in reverse, it will stall and not start till it cools down for hours.

I would start by checking to see if the ignition system is working while the trouble is occuring. If that is ok then check the fuel system. Try spraying some starer fluid into the intake.