I just seemed to notice this the other day, but whatever speed i'm at about 35mph, i can feel a slight stutter or hesitation in the engine and it does it repeatedly. I'm not sure if it's enough a passenger can feel but it's definitely not normal. I just recently had my haltech re-tuned, but all the numbers (a/f) seem to be good, and he never touched any fuel/ignition tuning.. Any ideas?

 

Have you checked the plugs?

 

The were just installed brand new less then 400 miles ago.