I do not drive my truck much these days, since I have a little geo that gets 37mpg for going to and from work. However the last time I took my truck on a drive the engine tempature did not seem to run where it normally does after it warms up, it ran below??? Should I be worried that maybe my thermostat is sticking open some? I pulled our 5th wheel with it and it ran a little above normal, which is what it has always done when I am pulling. Any ideas? Thanks!