every once in awhile especially when its cold when u start the truck it was surge and run rough like its not firign on all cylinders and the voltage light will be flashing, then i shut the truck off and start it again and its fine. Anyone know what this is?

 

i had a similar weird problem (no surges though) with my amp gauge (seperate post). turned out to be the battery. might be worth yout time to get it checked, i was told a defective battery causes strange electrical problems and could take out the alternator.