2004 Hyundai Santa Fe 6 cylinder, automatic, 4 WD. I recently had the timing belt replaced at about 65,000 miles by a Hyundai dealer -- recommended for Arizona because of the brutal heat in the summer. For about 2 weeks it drove as smooth as soft butter. Then it developed several symptoms that neither my regular mechanic nor the Hyundai dealer's mechanic could detect with the computer or by driving it:
-- Vibration that I (and my husband) can feel through the steering wheel when the A/C-Heater is off or on, whether moving forward or stationary.
-- On the highway at about 65 mph it will accelerate and RPMs will increase slightly on its own and then reduce speed and RPMs on its own.
-- The shifting from a mid gear to high gear is more noticeable and seems to hesitate
--- On the high speed gear (+), it seems to lug as if I had never shifted and the positioning does not seem to be as positive as one would expect.

My husband has the same experiences when he drives it so I am definitely not imagining this. I live in the Phoenix area. Is there a mechanic around here who can diagnose what the computer doesn't pick up?