2600 not runnig right need help???

I have a 2600 Fuel Injected and when the engine is first fired up it missis real bad and I rev it between 3000 to 3500 it smoothes out and runs fine. Then I can shut it off and fire it right back up and its okay. It almost seems that it is flooded but i dont think thats possible b/c its fuel injected.

does it also smoke/steam out of the exhaust? those trucks are known for bad heads, i have replaced 2 b2600i heads already. could also be a leaking injector. it could be a ton of things. anymore info?