ajschwab2004

I bought a used 2005 F150 with a 5.4 3V engine and since I had it it's hard to start usually just on the first try; if you try it on the second try it starts right up no issues. I have tried lots of things replacing the engine Oil/Coolant Temperature sensor (screws into the side of the oil pan), replaced Fuel Pump Drive Module, replaced the VCT solenoids in the engine, replaced the air filter, and replaced the fuel filter I even sprayed the MAF sensor with MAF sensor cleaner and sprayed the throttle body with throttle body cleaner. Another thing I tried is just priming the engine 5-6 times usually fixes the hard start, so I'm thinking it's either the check valve in the fuel pump assembly or the fuel rail pressure/temperature sensor? What do you guys all think might be the problem?