I have a 04 F150 5.4L. My temp guage is flucuating between C(cold) and normal running temp. I changed the thermostat but it has continued for the most part. My check engine light is still on after unplugging my battery. The engine is not running that well either so I went ahead and changed my fuel filter (just over 60,000 miles on truck) and that really hasnt helped either. I have a feeling its something with the computer/electrical. I would love to hear thoughts or ideas or if anyone has had the same problem....any explanations at all will be greatly appreciated. Thanks in advance, Clay

 

If the CEL is on, have you pulled the codes?

 

got the codes pulled. it was the coolant sensor....or something like that lol. thanks wildcard.
p.s. have yall heard of this happening alot?