Switching from efi to carb will cause more problems then correct. The computer runs the trans as well as the engine, so you would have to get a seperate controller for the E4OD(about $450). I am pretty sure the speedometer runs throught the computer also. I know it definitly reads its signal from the rearend. So that means you need to connect the speedo to the trans controller or something like it.
Your best bet is to modify the existing efi. cold air intake and exhaust upgrades will wake up the motor. Is the check engine light on? Try pulling codes to see if something is not functioning properly. There are a bunch of things you should consider before going to carb.
