Tim, X2 on Jerry's advice to check motor mounts. Tightening them up solved my problem. Even though they are new in your case, won't take long to check to see they're still tight and it would be the easy solution. Well, the easiest thing would be to intentionally slip the clutch and see if that helps. While in high gear at a 30 or so mph and going up hill just ride the clutch a bit causing it to slip. Not for too long, just enough to burn off any oils. May help and if not overdone won't hurt since few will ever drive there trucks to the point of actually wearing out a clutch.
Good Luck,
RonR
