Unfortunately its no a third gen but bare with me please. The project is a 1995 Chevy C1500 with a 5.7 and 4L80E. I first swapped the engine harness over to a 96 C2500 harness and repinned it for an 0411 conversion. The 24x kit came from EFI Connection. The repin and coil on plug conversion instructions were obtained from Lextech. Everything went fairly well. The long term goal is to run around 8 psi on this engine until I can build a proper engine for 4 digit power numbers. Planning ahead I opted to go with a 3 bar GM map sensor part number 12592525 and start out with a 2002 6.0 4L80E truck tune and applied COS 0202003 for 3 bar map, open loop speed density operation. Seemed easy enough. With the tune loaded and basic corrections made for a 5.7 vs a 6.0 (settings were obtained from a 2002 van L31 5.7 tune) the truck technically does start and run. It hesitates to start but once it does it runs very rough and after 20-30 seconds will start to smooth out somewhat. The wide band shows an average reading of around 14:1 at idle but then it randomly dips lean and barely stays running, then drops back into the 14:1 range and surges back to life only to do it all over again. As soon as I touch the throttle it goes lean and dies. All engine sensors are valid and the 3 bar map is calibrated and giving me a baro of 97 kpa at approximately 1100 feet elevation. I have verified all the injector and coil control circuits are pinned correctly. I did change the injector assignment in the tune but that only seems to be there for close loop fuel trim control and is irrelevant in my scenario. I believe the injector data is correct given the table I found. They are Magneti Marelli IWP069 injectors. I hooked up my timing light and verified the actual timing is within 2-3 degress of what the commanded timing is. I can't do a crankshaft variation relearn because the engine won't rev over an idle. I pulled the valve cover and verified TDC #1 and checked my distributor (cam sensor) timing to be as close as I can get it short of the engine running well enough to do a crank variation relearn. Mechanically the engine seems solid. Excellent oil pressure, cranks over very even and so on. No funny noises. I'm pretty much at a loss of what to try. Oh yes, the fuel system. Stock vortec 350 pump with a Corvette self regulating fuel filter with a verified pressure of 55 psi. Any help or recommendations would be greatly appreciated. I'll attach the chart I extrapolated the injector data from.

The engine specs:
stock bottom end with new crankshaft and bearings
stock pistons with new total seal gapless rings
mild port work 906 vortec heads with stock valves, PAC racing springs and Scorpion 1.7 full roller rockers
LT4 hot cam
Mercruiser Marine vortec multiport fuel injection dual plane intake, Edelbrock 90 degree elbow and 92 mm throttle body.