I just bought a 2000 Sebring Convertible with approx 130,000 miles. When I slow down it usually downshifts into first gear really hard. Sometimes it shifts ok into first, and every other gear it shifts to just fine. What causes this, and how difficult is it to fix it?

 

When is the last time the transmission fluid was changed? No idea, right? Might want to start there.
Another possible source of trouble is the solenoid pack. Search the forum and the web for information about that. If you're handy and have some basic tools, you may be able to do it yourself.
Those are relatively inexpensive things that may help. If these things don't do the trick then you will need to get it in to a pro who has the equipment and knowledge to diagnose it properly. Be prepared to spend some money. If you bought a 13 year-old car with transmission issues, I assume you didn't pay much, so now the expensive part begins. Better to address the problem sooner rather than later as it won't get cheaper to repair with time.

 

I hadn't thought about the solenoid pack, but I did consider the fluid. I was also thinking either the input sensor in the trans could be bad based on what I had found elsewhere on the forum. I guess I should start with the fluid first then.
Thanks for your help