In need of some diagnostic help

[trebor]

My wife, who drives the hummer about 3 miles to work each day, mentioned to me that it seemed like the brakes were dragging in the parking lot at her work. I just went with at test drive with her to see if we could reproduce the issue. It seems that part of what she felt was when she was parking she had to back up, so she shifted into reverse and hit the accelerator and the engine seemed to stall or shudder a little. Well to make a long story a little shorter, I was able to duplicate this every time I came to a stop and put the trans in reverse the engine seemed to either miss or stall out for about a full second, then seemed to accelerate just fine. When backing out of my garage I do not feel anything, just after the trans was in a forward gear first and then shifted into reverse.

Any ideas what this could be?

It has 2700 miles on it and I have already made an appointment with the closest dealer which is about 120 miles away to service it and also check to see why none of the dash lights dim when you adjust the rheostat.