Will, from all that I've ever heard, I would bet that your sending unit is toast. Mine always fluctated and went down to almost 0 at idle. If your oil pressure actually dropped to 0 while driving, you wouldn't have much time to register a rise in coolant temp before your motor went south. A new sending unit should do the trick. If that doesn't help, you may want to test the resistance of the sending wire with a multimeter. Also, a dirty connection to the sending unit, or bad gauge could also be culprits. Hope this helps -Ryan