Again,

I recommend checking the overboost / alda fuel enrichnment circuit. My old 300 SDL would run to over 4000 rpm with no acceleration. It would downshift... still no zoom. Once the fuel problem was fixed, at 2500-2800 rpm there was a very noticable boost. If you are not feeling this you are not getting enough fuel to match your boost. Boost with no fuel is no more hp. Good luck, hope you find the problem.

Chuck