I have had a code of misfire on 4,5,6 and random cylinder misfire code replaced coil packs spark plugs timing good compression good two induction services pcv egr valves good and cleared has anyone seen this issue the light comes on and off about every ten startups after idling to temp have refurbished or remanufactured cats on one and two and new o2 sensors down shifts hard only throws the misfire codes in the system but throws every other light on battery and alternator good aswell

 

Misfires on only cylinders 4,5,and 6 means something is wrong on bank 2 which faces the front bumper of your car. Since you read codes, does your code reader also read live data? Does the car downshift hard or have performance issues when the check engine light is off?

 

yes it downshifts hard and I do but it’s to long to send in here and does have power loss

 

I'd read the long and short term fuel trims on bank 1 (cyl 1,2,3) and bank 2 (cyl 4,5,6) when the engine is at operating temperature. Post the fuel trims at idle and at ~2000 rpm. Fuel trims jump around a bit, so post approximate values. You'll have 8 numbers to post on here. This will tell you how lean/rich each half of the engine is running.