Originally Posted by maxcichon

As a matter of fact, yes.

After 5 days wait, they called to tell me:

1) Only 1 Intake Mani gasket was sent. It would be at least 5 days to see the 2nd. (These are available for ~ $4 at at least 5 different vendors)
2) Please return the rental van or I would be over the $175/issue limit.

When I had it home, I stared at it for a while, then squirted a full can of MAF cleaner around and then attacked it with my trusty plumbers torch (not lit, of course!). I couldn't find any leaks. Do you think the dealer tech lied? Or did they mist a little carb cleaner into the exposed MAF/intake while it was running and figgered' they "got it"? That happened to me while I was looking. But, I knew what had happened.

Once the weekend arrived (next day) I decided "what the he!!?" I'll drive up and see my buddy alaxfire. Ran great. As a matter of interest-it ran better each mile I drove!
After I returned home, I installed my home-made/eBay oil catch can and tried it again. Runs fine.

My theory:

When I removed the MAF/elbow/throttle body for cleaning and inspection while painting my valve covers and intake manifold, I noticed that there was evidence of poor installation/alignment of these 3 items from either the factory or the dealer. Some dust tracks and asymmetrical deformation. I removed, cleaned and conditioned the 2 sleeve seals with silicone vacuum grease. (Wonderful stuff. Viscosity stable to 150 degrees C.) Replaced the really crappy silicone o-ring (TB/intake manifold seal) with a very nice Viton (medium soft) AS-151 o-ring.

All of the problems started when I fired it up after this. It ran poorly for 2 days. Then it died in traffic (idling at a light) and I had it towed in.

The codes I delivered it to the dealer with were:

P0101 MAF Circuit/Range Performance Problem
P0171 System Lean Bank 1
P0174 System Lean Bank 2

They were still there when I picked it up. They "fixed" themselves after ~ 45 miles of driving. No codes, showing or stored. That's right: the CEL went off on its own.

In short, I think that I fixed a long-standing vacuum leak (more than 1) and the ECU took a while to sort it out.

I am NOT impressed with Mercedes' "plastic hooks, clips and tabs" method of attaching these 3 items. Chintzy, cheap and unreliable. Much too easy too make a leak.

My thanks to: George, John and John. George scratched his head as much as I did when this was going on. We swapped out all 3 parts from his roadster, one at a time, to see if we could isolate a bad component. The 2 Johns for moral support and hand-holding.