Backfires at high rpms, except last night it did it even if I touched the gas until it died. compression at 120, fuel pressure at 50, scanner shows nothing wrong, new wires, plugs, cap, rotor, crank sensor. Sometimes it'll start if I pump the gas, sometimes I have to unplug and plug in crank sensor and/or distributor, or reset computer to start. Sometimes that don't even work. Any ideas?

 

if your not showing any codes during any of this, then id try a couple of things, make sure your battery is in good condition, as in 12+ volts when tested, the pcm will act funny and do weird things if the battery isn't top notch...also, try disconnecting all the pcm connectors and blowing them out with compressed air, and smear a little dielectric grease on the face of the connectors were the pins are, this has fixed some unexplainable issues for me in the past..

 

I've tried that and still doesn't work. And the battery is brand new.

 

See if you are getting spark when cranking the motor(both at the coil and the plugs). If so then it may be an issue with fuel delivery. How is your plenum gasket?
http://www.hughesengines.com/Index/p...p?partid=27091

 

It has spark on the coil and plugs, and its definitely getting fuel and I just did the plenum and intake gasket.

 

Are you getting injector pulse though?

 

Any chance you moved the distributor on accident? Could the plug wires be in the wrong order?