Hi,
Had the same issue regarding the stalling on my C43. It would stall on the first start up of the day when i would select drive. I found if i left it idling till the revs dropped slightly then select drive it would,nt stall.
It was intially diagnosed as a faulty MAF by MB, this did not solve the issue.
I got the gearbox filter and oil changed by PCS, and though this improved the gear changes it would still stall on first start of the day, though after 6-7000 miles it did seem to improve, the revs would drop very low when put in gear but did,nt stall, this only lasted for a few thousand miles and the stalling resumed.
It was the consensus of opinion that my Torque Convertor was failling, so when I had the 55 engine fitted, I had the gearbox and Torque Convertor refurbished, which has solved the issue.