1996 Saab 900 intermittently (approx every two weeks) fails to start (cranks but no start, wait 1 hr and will start). Fuel pressure measured 50psi so service installed T line into throttle body to reduce to 42psi. Still intermittently cranks with out starting (wait 1 hr and it starts), had fuel pump sending unit and fuel filter replaced. Today after running car for 1 hr., parked, came back 3 hrs later cranked but no start. . Waited 45 min. Cranked and started right up.Any ideas?