Just curious (and kind of thinking out loud here) but does the "stutter" between 1500 and 2000 RPMs happen all of the time or just when the engine is cold? Also, does it stutter when revving in park or only when you have it in gear? Not knowing if the OP has an N/A or and SRT, could the stutter he feels at highway speeds be the S/C kicking in and out (if it's an SRT)? I only ask these questions because my SRT has a stutter or hesitation when the engine is cold but it goes away after about 5 to 10 minutes of driving. It also only happens when in gear - revving in park it is smooth as silk. I've never really investigated it because it goes away so quickly, but I would hate for the OP to start throwing money at something that is not needed.

RL