coogan,
I have to agree with 53fatfndr about the injector size being too big. When I built my turbo 1.8L motor I was talked into putting 45# injectors in. Although I do have the so called power adder (turbo), I found that the 45's were way too large and controlling flow down low was a problem. At WOT it is no problem, but after a high rev run and coming back to idle my motor would load up on fuel and stall. 35# injectors have solved all these problems. For shorter pulses (idle to off idle) the volume of fuel is much more controllable and at WOT there is still more than enough to go around. Another thing to check is your pressure regulator. Are you recirculating fuel back to the tank or just regulating pressure? If things are too rich (so much fuel pressure that you are pressing fuel past the injector, or it is dripping) you could end up with unburnt fuel in the exhaust system which also leads to nice bangs! My 45's gave me plenty of opportunity to experience that.

Man, EFI is a bitch, or it is awesome! It just depends on whether it works or not!

Regardless of the problem, the plugs ought to tell you all you need to know. To rich they are wet, too lean they are whiteish. Next time you get it warm and it starts back firing, while in the backfiring stage, turn the key off and immediately pull a plug, or many plugs. This will give you a glimpse into that moment in time as to what is really going on in your cylinders.

Good luck. I went from adujst it with a screwdriver "webers" to EFI, and tuning with a laptop while fun, is just a whole different frustrating world. I can sympathize with you.

Brian
www.myturboalpine.com