I bought a 91 Accord SE with a blown engine. I put a 94 F22B2 in it with the head from the 91. Here are some of the problems I'm having. Engine light is on, S light flashes, wont shift into overdrive, engine revs up & down. Codes 12 & 17 flash meaning EGR & speed sensor problems. I believe my problems are electrical but I'm not sure.

Question is where do I start? Do I change the ECU to a 94? Could it be the TCU?