Idling #5 and #7 miss fire. holding it at 2000 rpms makes all 8 miss fire. its running really rich and the only code its showing is P0300 which is engine miss fire. have replaced plugs wires cap and button. dont know what else to do!!!
Cars & Trucks - GMC - K1500
Answers & Comments
When there is an engine misfire it could be gas or spark related. Or, the oxygen sensor may not be operating correctly, which controls fuel supply.
If there is a 'random misfire' then it could be an oxygen sensor causing the problem, as well, causing a rich mixture.
Good luck on this repair.