Hello, my name is Bart.

I have a 1989 6 speed manual tranny Ford F150 (4+ overdrive and reverse) with roughly 106536 miles to her.

When I'm driving if I am at 25 mph in 4th gear I lose fuel mileage at lower than 1500 rpm. If I stay in third roughly between 1700 and 2000 rpm I get phenomenal gas mileage. I'm not sure how to upload the video to show what I'm talking about but I was wondering what might cause that.

Theres a new air filter (4 months old) and with new oil and filter the effect is even more prevalent.

What could cause this and is it fixable?

If I am able to upload the video; I know the power steering is screaming and the taps are from the necklaces hanging from my rearview mirror.