Hi, I've got a 2001 Grand Cherokee, 4.0 with 123,000 miles. I thought my transmission (automatic) was going because while driving, I could feel it slip, and especially when getting off the freeway, it would not shift into 2nd, I'd have to pull off the road and re-start. Somebody put a meter on it and it showed a code PO123 which is the throttle positioning sensor? Is that something I can do myself or should an experienc mechanic do it? I just do basics around my cars, not into heavy-duty stuff, but if it's something that just unscrews and screws in, maybe I can do it.
Thank you.

 

It''s not difficult to change but I would advise checking it and its associated wiring before thinking about changing it. They usually last longer than that.