I have a 97 F250 LD Lariat 4WD with just over 50K miles on it. The last week or so, when driving down the highway it feels very "heavy" as if I'm towing something behind me.

The tires are at the proper pressure and the brakes appear to work properly.

Any suggestion on waht to investigate?

Transmission?
Tires? (still original so perhaps a belt has shifted)
Brakes?

Thanks.

 

You might have a parking brake that is stuck partially on . . .that would cause a drag . . check to see if you can feel any heat around your rear brake after you have driven a few miles . .and try putting your truck in neutral from road speed and see if your "drag" is still present . .if there is no drag when doing this, it is not your brakes . .i think the tires are an unlikely item . .if you think the drag sensation is only under acceleration and your coast down is normal, you could have an engine related problem