still new to this ,is it possible to have knock in vac with a good afr reading ? driving in 5th gear not in boost get cel around 2.75-3k rpm until i either accelerate or let off, was doing it all day today on a 250 mile trip to the track, always stayed lit short wile not a flash no stange engine noise and car ran great- but my one axle is going bad i guess and has a vibration, after the trip its now showing cel when coasting to a stop clutch in not in gear, i'm hoping the engine is fine - should i be concerned or just go about fixing the axle and other stuff ?