My transmission intermittently bangs 3rd or 4th really hard. If I restart, the problem goes away. Had it at dealer, but there were no codes. Happened two days ago, and again today. Today I got an error code for "transmission problem" and "Emission problem". Restarted and tranny problem went away, but Emission Problem error continued. Has anyone else had this problem. Car has 31700 miles and it staRTED AT ABOUT 30,000 MILES.