I have an Onan Genset. The unit ran well all summer but the last time we camped the unit surged and sounded like it wanted to go dead. I shut it down and it restarted and ran fine. When I returned home it has gotten progressively worse only running a few munites before it starts hunting and surging uncontrollably. I took the carb apart and cleaned it and I noticed that the intake tub had some type of gasket that was chipping away. I did not separate the tub in half to check the gasket. Could a leak of vacumm cause this? I also noticed there was also an oil leak at two of the bolts on the head at the center of the head. Could this cause the governor to hunt?

well if the gasket is not sealing then yes this will cause it to surge. you will need to take the gasket off and replace it. i dont think an oil leak would make it surge

I will check the gasket on the intake tube. What if the oil that is seeping from the head bolts is from a broken gasket allowing air to get to the cylinder of the valve section? Should I change the head gasket?

The headgasket would tend to push out air from compression, not suck it in.

DO replace that gasket on the intake..... oem, not make a gasket stuff.