The Mass air sensor was replaced about 6 months ago, no problems. I will change all fluids (including the converter) and hope for the best. It down shifts fine, and up****s fine under 3000 rpm. For higher rpm shift, I get a harsh engagement. It seems strange to me. No slipping, no other apparent problems. Just does not like to shift at higher rpms...

__________________
2008 S550
2010 GLK350
1997 E420 (retired)
2005 CLK500 (retired)