Help with persistent misfires

[drexer13]

I have a 2007 q7 that has had a misfire problem for a while now. It runs and idles great but when the rpm gets up around 4500 the the check engine light starts to flash.
When I check the codes it says there is a missfire on cylinders 1, 4 ,2 ,8, 6, and 7. The funny thing is those cylinders missfire when I'm accelerating, but if im decelerating and down shift to slow down then cylinders 3 and 5 start to misfire. I took it to the dealer a while back they replaced the fuel pump, the fuel filter, the spark plugs and coils and an intake runner actuator to no avail. I asked them about cleaning the carbon off the intake valves but all they offer is a some sort of cleaner they spray in the intake while the engine is running so I ordered the parts and did it myself. Still have the same missfire. If anyone has any ideas that would be very helpful thanks

[mikeA602]

try checking your PCV my c5 4.2 misfired at idle and i got a few flashing CELs also was like a $80 part


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[staypuft]

I gotta put new plugs in mine often to keep it idling nice.

+1 on the PCV