Took the DISA out of the conv and cleaned it, cleaned up whatever I could reach inside the intake, cleaned the MAF, and cleaned air filter on the performance CAI too. Broke that stupid little F connector on the upper intake boot necessitating a trip to the dealer. All done now, eliminated the 3K studder. Pulled the spark plugs and all looked good, only 36K miles on the car so wasn't expecting any bad news but wanted to check just the same.
Got an awesome CF license plate holder in the mail today from Williamsburg, looked better on the TIAG than the IR or Topaz, so that's where it went. Gary coerced me into letting my son debadge the TIAG, so that was done too.
Let Gary drive the 540i, he might now be an E39 convert, time will tell.