Hi, I got your PM, but I'll just answer here, because you have the info I requested in PM.

CKF is a new sensor for OBD2, from what I understand it judges misfires, by measuring rate of change of crank. On the OBD2 motors it lives on the oil pump.

OBD1 motors didn't have this sensor.

Sounds like you're running an OBD2 ecu (if it's still the GSR ecu, that's a poor choice).

Solution 1: But a ecu conversion harness and OBD1 P28/P30
Solution 2: Replace your OBD1 oil pump with and OBD2 one, and run the appropriate wires.

-PHiZ