94 gsr into 92 cx

okay, im havin major issues we got the car started runnin in limp mode was throwing tps, iat, iacv codes. got those cleared up, car was running great, i got back in and revved it to around 6500 and all of a sudden the tach jumped way up, the speedo jumped around, then it cut off, now it only started like 1 in ten times, everytime i hit the key the speedo jumps, when it does start it cuts off immediately, or it runs for a few seconds. then all of a sudden it started a few times ran perfectly!! then back to the other crap, can anyone help me i cant figure this out! has anyone had this issue?