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Did the tuneup. Replaced all plugs, spark coils, did oil change. Plugs all looked evenly worn with even deposits on the tips. Coils were in good condition but I replaced them anyway. Cleaned the MAF, replaced engine air filter. Engine pulls better now, and is a bit smoother when shifting.
However, the tuneup made no difference in the vibrations or random engine speed.
I was able to pull the long term trim values for the engine and they are at ~+12-13%. This indicates that the MAF is weak, or there’s an air leak somewhere. Tried running with the MAF unplugged and took a short trip. This seemed to stabilize the idle speed and car ran well without it. After plugging back in the engine again was not settling on an idle speed and having weird behaviors. I replaced the MAF with a genuine Porsche Bosch sensor at about 60K miles. A little upset that the $300+ calibrated sensor has a life of 30k miles. Cleaning it had no effect and my trims are still high. Still have same vibrations with MAF connected or disconnected. Will do a smoke test to check for any air leaks before replacing MAF (this was done just a month or two ago by a Porsche mechanic).
I'm almost 100% convinced this is a DMF issue. I know the DMF hasn't been changed for at least 50k+ miles. If anyone has other ideas, I'm all ears to hear what you have. It's a major PITA to replace the DMF so I want to run through the easier fixes first.
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