2000 GMC Jimmy 4.3 Vortec with 129K miles, doesn't want to start too easy when engine is warm or hot. Starts fine when engine is cold and been sitting overnight. New Plugs, Wires, MAS cleaned, new air filter, engine runs fine once started. Starts in milliseconds when cold, but after engine warms a bit,,takes several tries to get it going. cranks Ok, but like no fuel or fire. Has New battery. Has new fuel pump, pressure check oK 60 PSI ON FUEL PUMP, HOLDS PRESSURE FOR A GOOD HOUR OR MORE.,,,Don't think it is leaking down,,don't smell gas around engine,,no gas in oil. believe it may be electrical or wiring problem...could it be ignition switch? or temp. sensor or crank sensor?