2003 Chevy Trailblazer Car hesitates between 40 and 70

What is the condition of the trans fluid. How many miles on the vehicle but by what you are describing
there is an internal transmission problem take the vehicle to a reputable transmission shop and have them remove the trans and do an internal inspection.

Had same problem with my trailblazer. Felt like it was missing a little but no engine code. 1 mechanic could not find a problem. Did have 2 injector coils replaced and it helped a little. Gm then issued a bulletin claiming that this misfiring is inherent in this model of vehicle. The olds or buick was only all wheel drive and nothing could be or was needed to be done. By driving in 2 wheel high only (until 4x4 actually needed) problem seems to be minimal. My vehicle has 135k and trans was replaced at 35k under warranty. The tick occurred at about 90k but my wife had been driving in 4 wheel high all the time.