ok here's an update, we found out he had a pm9, which is a ecu for a civic std 4spd. so, we went to the yard and got a pm5 ecu for a dx 5spd, a new dizzy cap bc the other one was kinda messed up, and a Ebrake and center console assembly. after we swapped the ecu it ran better but still wouldn't rev over 4k. car ranked and idles better with pm5 ecu and new dizzy cap. So, we pulled the cluster and tried to hook up the cable speedo back up to make sure it stays hooked bc we never check the cluster. well it works but it keeps cutting out. i'm thinking that either the cluster is bad where the cable goes into it, or there's some type of clip that holds the cable into the tranny. it stays in the tranny but there's another clip that holds the vss in the tranny but i have like 4 of the clips. OR, the end of the cable is messed up that goes into the gauge. the end that goes into the tranny is fine it locks into vss no prob. so, could it actually be the speedo not working that's making it not rev over 4k? also is there some type of clip that holds the tranny end of the speedo cable that holds it in? could it also be the piece in the cluster that could be bad? does anyone have a 90-91 SI cluster? he wanna swap it out lol.