I have a 2004 cayenne turbo and was recently noticing a rumbling in the car at idle. After ruling out motor mounts, I eventually had a CEL pop up as p0308 for cylinder 8 misfire and p0300 for multiple random misfires. I checked durametric and found that I was getting misfires happening in cylinder 8 while the car was idling but when I would press the accelerator it did not seem to increase the misfire counter. I replaced the coils a few years ago and went ahead and checked them all again and did not see anything wrong or cracks. I also change all the spark plugs at the same time. To rule out a coil, I moved the coil pack from cylinder 8 to 5. After all this, I started getting the cylinder 8 misfire code again. What should I be looking for next, fuel injector issue, bad wiring, compression problems in that cylinder. The valve cover gaskets were also replaced a few months ago for leaks. What does it point to that misfires seem mostly to occur with idling