Hope this is fixed by now. I had the same problem. It ended up being a bad fan clutch. If you are overheating make sure not to overlook that as well. From the interwebs:
"To confirm the diagnosis, start with this simple test: Spin the fan as hard as you can on an engine that has not been started that day. If the fan rotates more than five times, you can bet the clutch is bad. You should feel some resistance and the fan may spin up to three times, depending on the ambient temperature."
