I am tuning a engine swap, we are using an early 2000 5.3L lower and a 2007 Tahoe intake, injector rail, throttle body, using a E40 control module. The engine has had a large camshaft installed. I have successfully gotten the engine to run and even idle, however it is really rich and is extremely sluggish, back firing (intake and exhaust) when trying to accelerate. Not setting any codes not even a rich O2. Exhaust headers glowing red when running over 1500 RPM's. Anyone have any suggestions?