Title self-explanatory. A little more insight: after it's warm it usually hovers around 500rpm and lower, almost feels like its wants to cut off. Battery is fine, all grounds are fine. Only other thing I haven't checked is my alternator. Have a CEL for o2 sensors (not installed yet) and the notorious CKF sensor (jdm engine w/ USDM ecu, haven't performed the CKF trick yet)

Would the CKF code be the prime suspect?
Any help/ info would be much appreciated.

Thanks H-T