2000 CLK430 low power on downshift/passing
 

Hi guys I am on vacation and have been driving my buddies CLK, car runs and drives very well with two exceptions, at idle, it is a little off, not sure if it is low but it is very slightly rough, all of the V8 mercs I have had have been nearly silent and vibration free. Secondly, and more importantly, when you are driving and kickdown, the motor revs but there is no corresponding rush of power once the car downshifts. It does not feel like the trans is slipping but almost as though it puts itself into limp mode. In normal driving the car shifts smoothly and consistently. Only occurs under downshift and hard acceleration. The car has intermittently thrown a P0405 and I have cleared it twice in the past 6 months but is not throwing any other codes and the CEL is not currently thrown.

TIA

Doug

Any ideas at all? I am stumped as well.