The sensors you replaced in the head are seperate from the fan system. One is used for the ECU (ECT - Electronic Coolant Temp.) and the other is for the Temp Gauge in your cluster.

The fan switch is located near the Thermostat housing, where the lower/rear radiator hose connects. The Fan Relay is also a possibility.

If a thorough flush didn't help with the cooling problem, I would bet on the water pump as others said.

Before you spend any more money, is there any coolant in the oil? Or did you notice oil in the coolant you drained out?