How about a few specific details? What year/model chassis, which ECU are you running and what are the actual ECU codes it's kicking back?
I'm think I'm finally at the end of debugging my ZC conversion, 1989 JDM Civic ZC into a 1990 Civic Si with '89 teg ECU. It's been a 5 year process that included swapping in a new timing belt then finding the problem was a shot sensor in the distributor.
I was recently having it "idle' at 2500+ rpm and sometime strobe 2500/3500/2500/3500/2500/3500. If I was lucky it'd kick the check engine light on and go into limp home mode... error code 6.
Turns out the gent who did the conversion for me hooked up the TW sensor and pulled the lead TIGHT to get the harness clipped into it's holddown. So the temp sensor lead was making/breaking contact all the time.
The temp sensor is right under the distributor, the round connector with 2 leads.
So, what are your specifics?
Cheers,
Jim