MPG change, where to start looking? Options

[914Bryan]

I know this isn't an exciting high performance question, but a question just the same.

I'm having an issue with the mileage my 74 2.0 DJet and am wondering where to start looking for the problem. I commute 60 miles each way to work (120 total). My driving is 98% freeway, non rush hours so a steady 75 mph, motor is turning 3200.

I could always count on 32mpg, day in, day out. Over the last two months, it has slipped to 28mpg. I burn a tank a week, so this has been about 8 tanks of gas that I have noticed this.

Engine is running fine, no change in performance.

Would a tardy valve adjustment cause this? I'm a little over 6k since my last one.

Any ideas?

[914Bryan]

Thanks everyone, this is all great advice! Most of it is an easy fix, other than the valves, but I know they need to be done..Now I have somthing to do on Monday. I never consdered that the rear brakes might be dragging, guess I will check that when the ass is off the ground.

The fuel thing is beyond our control. Sad that it has come to this, but what are we to do? Buy 55 gallon drums of unleaded racing fuel? My friends that are into sandrails and off roading always buy their gas this way. Big 55 gallon drum of gas with a hand pump. I wonder if its cheaper and if it can be had without alcohol. I also wonder about storing that in my garage? Some fireman may not appreciate it if my house goes up in flames.

Anyway, I will let you know what I find out after getting my hands dirty!