Car stalls at about 10-15 minutes and won't restart

Car starts, exhaust begins to get rich after 5 minutes, car cools and restart is possible. Replaced the following: fuel pump, idle air control valve, new spark plugs, coil, wires, ecu/engine computer, oxygen sensor, cleaned throttle body, fuel pump relay. 1year prior the timing belt, coolant temp. Sensor and cam shaft sensor were replaced but no stalling problem until now.