Bought truck new and it's been pampered. Is a 97 XLT, 4.6, automatic, 3 door with a tow package.

It has been a very good truck and only has 138,000.

My concern is engine clatter at highway speeds. Engine starts and runs well. But at highway speed, under a load such as climbing a hill, it begins to sing, soundslike valve clatter.

Going downhill ormoving level there is no clatter that I can detect.

Vehicle has been doing this for several years. For the past couple of years this vehicle has been driven less that 5,000 miles per year.

With lower gas prices, thinking of driving it again full time.

Any suggestions on how to fix? Is there any reason for concern?

 

Start simple; run some Sea Foam in your gas tank and see if cleaning the carbon build-up out of the engine makes a difference in performance.