Vlotage Spike

Hey guys, I have posted about this problem before but now have more info to help diagnos the problem. While driving my 97 tahoe (4wd 5.7) the engine will start to surge. The airbag light is flashing, I have no throttle control and the volt gauge is pegged towards the high end. This last for about ten seconds then the transmission shifts extremely hard until I shut the vehicle off. Today this happened again and the fan for my heater stopped working. I got back to work and there is anti-freeze leaking from it. I bought a new IGN switch but have not put it in yet. I am thinking this is not what is wrong. Is the anti-freeze shorting out some wires? Any suggestions would be appreciated. Thanks