Hi everyone. New to this forum. Anyways my mom has a 2003 monte carlo pace car. Great car shes had it since new. Only problem I borrowed it from her the other day and when i was driving down 80/94 the speedometer read 54 mph at 2500 rpm. Now I'm not stupid theres no way in hell i was doing 54 mph it felt more like 90mph. Then as i slowed down to get off the expressway speedmeter slower went to 0 and stayed. This has happened to me and only me. The heat was off (was about 50 degrees out that night) but heat was coming out of the vents. I think it just got too hot in the car for the computer but I'm not sure. Any ideas would be greatly appreciated.