I recently swapped a 1999 B18B1 stock motor back into my 1997 RS and now I'm experiencing occasional bogging. I'm using a stock 1997 LS ECU, stock everything with the exception of an intake and a dynomax chambered muffler. I'm getting no CEL's and no codes even if I check for them. It seems to run fine until the motor is warm, then the throttle is really sensitive and it bogs down. After running it for a few minutes at operating temp, it's fine and no longer bogs or hesitates.

I've reset the ECU multiple times, letting the car warm up on it's own (idling). I checked for vacuum leaks, replaced the TPS (and calibrated), and changed the fuel filter. The timing is slightly advanced to keep it from stalling (which it randomly when first installed). Any thoughts to what else it might be? NO CEL's!!