I recently bought a 300, it had 170000 miles on it. When I test drove it nothing felt wrong what so ever. Week later it started turning off by itself in the middle of the freeway or alleys. Got it fixed. But now when I am at a red light with my foot on the brake, the RPM doesn't go down to idle rpm at all. & it wants to take off on its own while my foot is still on the brake. It gets real shaky & it makes a loud engine noise.
It just recently started happening as soon as it got to 200k. Is it my transmission ?