Drive a lot of highway miles on an '02 Quadcab w/ rebuilt 4.7 (overheat - 8/07) with 133K. Recently felt a sudden load at 75mph, cruise control, but no engine light. Felt like truck had no power upon acceleration, almost like it was stuck in second gear. Took to local mechanic and they diagnosed a bad fan clutch. Less than $150 bucks (cheaper than a car note) and on my way again. Just FYI, I know I could have replaced it myself, but part and diagnosis was 75% of estimate, figured it was worth the $25-$35 to not get my hands dirty.

 

Right on man. A fan clutch puts alot of load on your engine even when it IS working hahah. If you got some extra cash an e-fan is nice to have!