Car has a rough idle, kind of like a loping, where you can feel the engine shake at certain intervals. Feels like one cylinder has pre-gnition. CEL and Maint Req light. Bought the car at 180K and it always took a few seconds to start, but that has gotten worse.

The first Autozone code scan showed #1 misfire as top issue, then 2,3,4,5,6 misfires. Got a Diag done and he told me the rear upstream O2 sensor was bad and to replace that first. Did that and the CEL and Maint Req light came back after a few minutes. Acceleration is good. Cruises at highway speeds just fine.

Belt, tensioner and pulley are new. All the plugs and coils are new... Any ideas?

Thanks in advance!

 

What are the codes numbers, like P1234, that showed up?