Check the oil level several times.... make sure its correct and not over filled. (Ive seen over filled cause what you describe before)
Check the TB's (again) Do you know if they turned up the "white hash marked throttle body" and then synced the other ?
You said they changed the plugs, make sure the four wires going to the four ignition coils are plugged into the CORRECT spots !
Did they perform a valve adjustment ? If so, could you please provide your starting numbers & and then what numbers they then changed them to ? (IMOP- ALL customers should leave the shop with this info, ALWAYS)
When you said you pulled the clutch in at speed and the vibration continued, did you let the RPM's drop too 1100 when you pulled in the clutch? Or did you maintain the RPM's at 4500 when you pulled in the clutch and you still felt the vibration.