OK. Have almost thrown the kitchen since at it now, just switched the oil filler cap for a new one. Only time I have seein anything other than P0170/P0173 (2017/2086) has been an occasional "pending" P0410 that never sets.
Keep in mind this is an early '00 SLK320 (same driveline as Crossfire just prefer a retractable to a soft top) so the ECU progam may not do everything a later car can. I have checked out the whole SAI system and is good/clean but only see it active when cold, never when warmed up. That might be a later revision.

The sudden spike at the grocery store I have to wonder if part of a learning process since when back down and has not repeated.

Posting here because of my coupe (no problems or codes) and people here are more technical tham the MB forums. Dual was the first to mention the swapped sensors. Have not seen screwy clong term cycles since.

Photo is of momentary spike (enough to set both codes) at the grocery store within a minute of starting and in Park (slightly higher idle and better manifold vacuum). Bright sunlight is not good to photograph a display. but is legible.