car cranks, spark is there, fuel pressure "seems" to be there, and you have checked:
--25a inline fuse, and it's ok.
--spark at all plugs, ok.
--jumpered fuses 4 to 6 and pumps run.
--fuel pump relay is good.
--main relay is good
--unplugging and plugging the air mass meter has no effect.
--battery does not fall below 9.6 volts during cranking
THEN consider this (what I learned the hard way):
when jumpering the #4 & #6 fuses, be sure to jumper across the #4 fuse (forcing fuse into the circuit), and maybe it might blow, like it did for me. I was at my wits end by that time and finally took it to the local mechanic, who confirmed a bad main fuel pump. The pump "worked", but not well enough to supply all the pressure needed to start the car. Guess the injectors need more pressure than what loosening the connection at the fuel rail leads one to believe there IS enough pressure. The mechanic sprayed WD40 into the air intake and the car fired then sputtered....what he called a dead give away pointing to the main pump. All this after I replaced the fuel filter, plugs, wires, cap, and rotor. Battery had also failed, and got replaced. Car oughta run GREAT now!! :)
maybe this will help a few folks out there.
--Tyler