Well the shop couldn't find the issue without asking for another $300 or so for a longer analysis, so I picked it up yesterday.

When I was shown a picture of the transmission fluid level, I noticed there are 3 separate brackets on the indicator:

The lowest bracket which is about 1/4" wide between the bars, a middle area which is around 1" wide, and a high level bracket also around 1/4" wide.

My level shows at 2/3 up on the larger middle bracket, it that filled enough to prevent the issues above?

The mechanic said that's the level they fill Mercedes 722.6 transmissions and never have high idle issues or P0505 or P0507 codes afterwards.

They also claim the Conductor Plate and connections from it checked out fine, there were no vacuum line leaks, and they cleaned up the Throttle Body.

Codes pulled off of Mercedes diagnostics were:

P20A2 - Idle speed control implausible:check system for unmetered air

P202B - Idle speed control implausible: (P0507) Short circuit to ground / open circuit (P0102)

Thoughts?