Originally Posted by K_E_N
pat, if you run hot at idle and not at speed, I would strongly suspect your circulating pump. With that pump, there are several possible problems.
Be absolutely sure that your accessory belt is on correctly. I've seen the belt on some cars that has been put on so that the water pump is turning backwards. This will allow a slow flow of water. Check the impeller on this pump. Don't just look at it and assume that since it looks good that it is. Sometimes the impeller can spin on the shaft. Hold the impellar while trying to turn the shaft by hand to assure that it's still tight. It's a pressed fit and can corrode, thus becoming loose.
One other thing is a faulty thermostat. I would completely remove it and see if that helps, just to rule it out.
Keep us informed when you finally find the problem.