jghoghunter, there have been a lot of people who've experienced something like a 'miss' under very light (sustaining speed on level ground) throttle in the 55-60 mph range. It's been attributed to air, but I've had it disappear twice with our libby.
It disappeared the first time, when the dealer replaced the AFC/EGR, after they finally failed sufficiently to start (and continue) throwing codes.
After less than a year, it started coming back occasionally, but not too strongly.
It disappeared again when the SEGR was installed.
Nary a bump since.
My harness arrived yesterday, so any air-in-fuel matters should also be gone before too long...
Food for thought.
Mark