Looking for suggestions on why my check gauges light comes on occasionally?

What is your question?

The truck runs fine for a while, then the check gauges light comes on. The battery gauge drops to 8 and the Oil Pressure gauge goes up to 110. This happens when driving 65 or sitting still in park. The gauges go back to normal after a few minutes and the problem might only happen once or twice a day. If sitting at a stop the idle is rough. It feels like it is going to stall, but hasn't yet. As soon as the gauges go back to normal the idle goes up to little higher than normal and then settles down to a normal idle. When the problem happens at 65 mph the engine sputters a bit but keeps going. Looking at the computer I got a PO720 code. I replaced the output speed sensor and I'm still seeing the same problem. Any ideas?