After vehicle has been driven and stopped for multiple times or for a long period and then stopped for 1/2 hour to 1.5 hours it will then stall within 30 seconds after the next start. Sometimes it will start and then stall again multiple times. Sometimes it will be O.K. Occasionally, it will not start and has to be left alone for an hour or more. Never happens on a cold engine left overnight. Sometimes on highway it will try to stall, but speed usually keeps it going. Dealership could not recreate problem. I changed plugs, distributor cap, rotor, plugs, fuel filter, and fuel pump relay switch. I swapped computers, Air Mass Meter. I tested with ohm meter coolant temp sensor, throttle sensor, air valve, oxygen sensor. Even tried disconnecting electrical connectors from sensors and driving. Problem still exists. Only clue is that it appears to only happen after car has been warmed up, stopped for awhile, and then restarted. Help!