[JERKY420]

you might want to recheck your thermostat there might be a piece of crap stuck in the thermostat holding it open and not slowing the flow of coolant and not letting the engine heat up. I would not flush the system if it is staying cool that means there is no blockage in the system. Also does it heat up to peak temp fast or slow, fast would say a possible guage problem also, and slow would be a good sign of a thermostat problem.