I have a 94 4.3 Vortec 4x4 S-10 that starts hard after it has warmed up. I just replaced the wires,plugs,cap, and cleaned the EGR valve. It has a new fuel pump and sending unit, new fuel filter. The truck runs great after it starts and starts right up when cold, I did a vacuum test and checked out good, but after running awhile it has to crank over alot to start, any ideas? TIA