i just got an 01 dak w/ a 4.7/5spd/2wd and for some reason when i am cruising on the freeway its will start to run hot from time to time for no apparent reason and i was thinking it could be the thermostat but that didnt rele make much sense to me kuz its fine runnin in the city.

 

maybe an air bubble in the coolant??? see if you can "burp" the system and top off the fluid

 

already did that thats one of the first things we tried, its actually my buddys truk but he asked me to try to find somethin out for him

 

Sounds like a thermostat to me. Thats how mine acted when it went bad.