Well, if your not shure on a few things, get some books that cover 350 TBI's, even though people say stay away from haynes and chiltons, chances are the book you need is available at napa. it sounds as though, the speedometer is not hooked up right. You want hi- po, you have an '89 so you may need the FI system to pass the knox testing, but upgrade to a MPFI system available through summit racing, a cam. and a set of headders. If you want to rid yourself of the computer, and run a carb, you need a carb manifold for '87-'95 Blocks, and you may want to get a painless wiring harness for your car, sounds like yours is a little messed up possibly. If the dude b4 you, swapped a 350 in where the 305 was, and used the 305 TBI setup, it's deffinetly in need of a new manifold as the injector port sizes are diffrent between the 305 TBI's and the 350 TBI's.