On the way home from work today I was cruising down the highway and I turned the heat on. Well, I looked down and my tach was going crazy. So i turned off the heat and it stopped. Then I turned the heat back on and it started doing it again, so I turned it off. Then when I got to a stoplight I turned it back on and then my car just died. Then I tried starting it and it fired right up. What is wrong or what could be making it do this??

 

I'm guessing that you may have some connection issues. Start by checking the grounds - battery, cable, ground node on the inner fender, and rear of the right head.