OK so I did a motor swap in my 97 EK hatch (ODB2A). I put in a 94 LS motor (ODB1). I hooked up the hatch's wiring harness to the engine, and I am still using the ODB2 ecu. I can start it, but when it is cold it has a real rough idle (bouncing idle between 1500 and 2000 rpm). Once it warms up the idle flat lines and balances out at about 1000 rpm.
After it warms up and i step on the gas to slowly and steadily increase the rpms it doesn't increase smoothly. between 1500 and 2000 rpms it still bounces, once it past 2000 rpm its fine. I do have a CEL on it says O2 sensor (secondary) and Idle Air Control Valve, but I have cleaned and replaced the idle air control valve part more than once and that didn't fix it.
Any ideas? Should I switch to the ODB1 ecu? (if i do this will I still be able to pass emissions?)