I have less than 15,000 miles on a rebuilt tranny (new 4th gear hub, solenoid, etc.) and recently it started acting up. It wants to downshift occasionally while the cruise control is on driving on flat ground, and today it shut off while shifting from reverse to drive, but it started right up and worked fine. Any help on where to start would be appreciated. I'm hoping I don't need to drop over $1000 again to rebuild something that will break.