99 cavalier flooding

Hi. I have a 1999 cavalier with a 2.2l. The engine recently was ruined so I found a 2.2 out of a 2000. Everything was the same except for the plugs on the injectors for the 2000 were a different style. For simplicity puposes I decided to put my 99 injector rack onto the 2000 engine. everything bolted up good and seemed ok. I installed the engine and tried to start it. I cranked it some and the exhaust started dripping out gas. I checked the intake and it was FULL of gas. What on earth would cause this on a EFI system??? The injectors worked fine on the old engine. I kept everything pretty clean when I swapped them! The intake seemed to fill up in a matter of a 5 seconds of cranking. Any quick fixes? The original injection rack should work with my original ECM!