I have a 99 f 150 5.4. The truck has a hard time starting I have to have the pedal to the floor to get it to start and when it does start it barly runs like its starving for fuel. Once it gets passed that stage when I push the gas and let off the tons stays at 1400 rpm for 3-5 sec then it jumps up to 1600 then right back down to 900, but does this every time I push the gas. I have checked fuel pressure 38 lbs at the rail. Changed MAS, IAC,Tps, any other ideas?