Running down the road 40mph+, I get high water temps. High enough to where my CEL comes on. Let off the gas, or come to a stop, temps drop and all is fine. I would think the temps would go down, as the water pump spun up? I haven't done anything to troubleshoot this. I did replace the upper radiator hose, but that was due to a almost blown out hose. Would the thermostat sticking close cause this?

 

id say yes. swap the stat and see what happens.