Earlier I had an issue with my enginge running slightly above normal and using up quite a bit of coolant (I used water to see if it would evaporate). After running a while my coolant level dropped drastically, and the temp gauge rose to about 3/4. I checked the fan/clutch, water pump, so finally I decided to change thermostats. My fan was kicking in and trying to cool the radiator, but the thermostat was locked up and would not let the coolant flow freely. So here is my method for changing out a thermostat. Materials: New thermostat $20-30 at your local auto parts store O-ring $3.00 Rag (for wiping and cleaning up) Bucket to drain fluid 3 Gallons of anti-freeze (depending on enginge) Channel Locks 8mm socket 10mm socket Water hose (if you plan to flush, recommended) Cascade detergent helps! Air hose/nozzle (for cleaning hoses and pipes) *I always remove the negative battery terminal before doing any work to the truck* Make sure the truck is cooled down quit a bit before proceeding. First step is to remove all 3 bolts holding your plastic 5.4 cover (over the throttle body). These are all 8mm. Removing air intake and accessories. (8mm socket/flat head) Now we need to take the air intake off to have room to work. 1.) Pull out the two hoses at the top of the intake. 2.) Unplug the MAF (mass air flow sensor) plug 3) Then unclamp the clip that holds the air box/filter in. 4) Finally loosen up the C-clamp attaching to the throttle body with an 8mm socket. You can now lay the air intake up out of your way, it is not necessary to unplug the air filter sensor. But if you want to take the complete plastic intake off unplug the following plug below. Laying it out of the way.