Q&A

This transmission does not really respond to any kind of band adjustment like older transmissions did. A fluid and filter change may yield some results, but based on the age and concerns described, it sounds more like you have more significant issues internally. If you have slipping between gears, it's a sign of internal wear.

Your "ker-chunk" issue - sounds like you have a broken motor mount or two. This is common - the "front right and left" motor mounts tend to be broken on these, and then every little thing makes a clunk and a lurch feeling.

This vehicle does not have a U-joint...being front wheel drive, it has two CV Halfshafts. http://repairpal.com/cv-half-shaft-assembly Check that link for further info on what those are and how they work.

The engine racing issue and check engine light - simply put, you need to have an engine performance diagnosis performed to determine what is at fault. You could have an air intake leak or a sticking idle air control valve. It may or may not be related to your check engine light.

Sounds like you have quite a few things that need attention - but everything can be addressed. Your biggest issue will be deciding on whether or not to invest in a remanufactured or used transmission to repair your slipping unit. Good luck.