Look for an exhaust restriction- - - - -Loosen the pipe flange where the exhaust pipe meets the manifold- - - -about a 1/2" gap will be plenty. I've seen a few mufflers packed with acorns by squirrels or chipmunks, and the vehicle won't get out of its own way. Take a test drive and see if the speed improves. Ditto for a restricted air cleaner. Engines have to breathe to make highway speed.
Jerry
I didn't consider that being a possible issue before, but thinking back there is definitely a crunch in the exhaust that I've seen under the truck. It didn't look bad, but it can't hurt to move it up a few notches on the "fix" list. Once I get a new bottle of mixed gas and a bit of tubing I can chop it off and weld a new bend in. I'll try your manifold-loosening method first though.
