Try the camshaft sensor since you have already done the RCM, CPS, fuel filter and pump.
Measure the battery voltage before start - 12.1 or better ?

Actually, the 6 to 8 times with the key indicates low fuel pressure even though your have replaced that junk. Try measuring the pressure at the fuel rail test point passenger side front of the engine.
Should be over 50 lbs/sq inch.

Is the compression OK on all 6 cylinders ?