I've got a misfire randomly between 1.5k-3k but I can power out of it. I pulled the CEL and I believe its a 41 Primary oxygen sensor heater. Could this be the culprit? The car is a 95' GSR all stock except for a Greddy EVO 2 catback I installed a few days ago....

Also if the CEL pops up and I turn the car off it will not be there next time I drive the car sometimes.

 

Dose it state wheather it is heater circuit high or low. Most likey it is your o2 sensor has failed, causing you to over fuel and misfire