2005 Tahoe Z71 5.3 Lost Fuel Pressure and Spark

My Tahoe started acting up, I found the MAF was bad changed it and went
ahead and changed the MAP. Saw the water pump leaking a little bit so I
changed it and the thermostat. Saw a sale on AC Delco plugs and wires and
changed those too. The  Tahoe ran a bit better then started acting like I had
water in my fuel tank. Random hiccups then it started dying randomly while
driving down the highway. But would start right back up...I figured my fuel
pump died, so I checked the fuel pressure and it was fine but the motor cut
off and pressure went to zero. I tried to restart and it wouldn't. Long story
short I pull off a plug wire and notice its not firing either. Now this is
weird.Crank sensor? Cam sensor? both? ECU? Security system? what else
could cause the engine to lose fire and fuel pressure? Thank you in advance
for your help. My mechanic has it now, but he's slammed with other jobs and
is having to pinpoint test every thing and I'm hoping I can take him a good
answer and peace of mind for myself.