ECM
 

I just did a 305 swap to a 350 in my 1990 Rs . And I read that I need a 350 ecm unless my ecm last 3 read 746 . they do read that . But now does that mean I would have to get a 350 prom ? Or what to make it run right . I have the 350 TBI on the car , and I dont have anything else replaced for a 350 ? I really need help this is the first TBI 350 swap form 305 I have done . All info would help thanks