Had the same P0715 code on my 1999 ML320 4 Matic 722.5 trans and did the same steps as you up until resetting the transmission adaptive mode. I ran through this sequence before driving:

- Turn the ignition key to the on (not start) position
- Press the gas pedal to the floor and hold for five seconds
- Turn the key to the "off" position (don't remove the key), then release the gas pedal
- Wait at least two minutes for reset

This supposedly resets the trans adaptive settings back to factory settings until your driving habits are re-learned.

I also erased the P0715 code with a generic OBDII reader.

So far we've been driving it daily 2+ weeks with no problems. Still, I ordered and am waiting for a mutliplexer to arrive so I can hook it up an also erase the transmission control module codes. My local Indy would do it for $90, but the mltiplexer was $105 (Dealtime.com) so I made the investment.

Kontoboy