I have 05 X5 3.0 M54 engine, I got the codes p0303 and p0306 misfire detected on 3 and 6, I changed the spark plugs swapped the coils to see if the misfire moves, but still on cylinder 3 and 6. Things I have done so far:
- Changed all 6 spark plugs.
- Checked the coils by removing it one by one while the engine is running.
- Checked the DISA valve, looks good cleaned it.
- Cleaned MAF.
- Changed valve cover gasket. I found some burned oil(not sure if it's oil but something burned with bad smell) on the spark plug number 6 that's why I changed the gasket.

I don't know what to do next, it gives only these 2 codes, misfiring regardless of the condition, cold warm or hot, idle or driving.

I need to mention that when the problem started a month ago, if I let the car run for a while and then restart the engine the misfire is gone, but now it's misfiring regardless.

I appreciate your help