Are tune-ups worth it??? Uhhh.. yeah. Depends though on what you're trying to accomplish with it. Is it going to fix all your problems? Can't say. Depends on what exactly is covered in the tune-up you've been quoted. Most of the tune-up just include the main things that you can do yourself, unless of course you can't do tune-ups and that's why you're turning to the dealer to begin with.

I can't speak specifically to your problem; but if your car has enough miles on it and/or you've never had it done before, you can at least have the tranny fluid changed (NOT "flushed"). Sometimes just getting some fresh fluid in there will smooth things right out. But I can't diagnose your problem specifically. That would be what the dealer could do for you...