It could either be your sensor or your thermostat.Check the temp of your hoses and see how warm they are.I had to replace the sensor and thermostat on my engine , my thermostat was shot , ran cold , and the sensor was shot too.Took me all of 20 minutes to change both , and I think it cost me 20 bucks in total.I do get a discount at a local parts store <img src="/forums/images/graemlins/smile.gif" alt="" />

1996 Jeep Grand Cherokee 5.2 with mods.Hughes Air gap intake , 52MM TB , ford injectors, 2 3/4" lift, Doug Thorley headers , HID headlights with LED , HID fog lights , glow gauges , a few others