I have a 08 gt with a auto transmission and I recently just started expecting this issue it's happening a few times where the RPMs would climb to 2k I'd tap the gas it would go down well I backed out of the driveway and it started climbing put it in park it jumped to 4k RPMs car has 174k miles well taken care of it sat for two years before I bought it but it's my daily and my first car any ideas what it could be