One of the suggested upgrades on here is a lower temp thermostat and lower temp (VW Vanagon) fan switch. Also, look at the directions for bleeding the air out of the cooling system, an air bubble at the top of the head can cause all sorts of cooling problems. After 100K the head gasket also starts to become suspect. At 110K I had the gasket replaced and the Variocam pads and chain replaced as well. The pads were in OK shape (the PO ran the right oil) but the gasket was really showing signs of age.
There is a lot to learn about the eccentricities of these cars, but the payback is they are a blast to drive. You may want to start a list and try to do as much as possible in a single trip to the mechanic. Belts and rollers are a given, but while in there the water pump is pretty easy to change, and the thermostat lives in the pump, so that's a simple fix at the same time.