I was driving on the Interstate when the road became very bumpy and all of the sudden my speedometer quit working. I pulled over and turned off my engine and it worked fine. Then I went through some bad roads again and it kicked it on and off. They problem that I am having is that my transmission is acting funny. 1. It downshifts on its own when the Speedometer quits working. When this happens, my RPM goes up really high and the Turn Off Engine light turns on briefly on the Dashboard. 2. When I slow down, it goes into NEUTRAL on it's own. 3. I can't use my Cruise Control because if the Speedometer fails, it makes the RPS skyrocket and I am afraid it will blow my gears. Advice anyone?