With everything on the truck that is in my signature my MPG is anywhere from 12.5-13. I feel like the truck should be getting better than that. The truck has about 197,000 miles and weighs somewhere in the 10,000 pound range. Looking for suggestions.

Is yout vp44 going out? How about your injectors? What about valve lash clearances? Are you adding 2-stroke oil to your fuel? Are you purchasing fuel from places that continually deliver quality fuel? What about the fuel composition? Is it no. 1 or no. 2? TONS of variables that you have to take into account...

I checked all the valves about 20,000 miles ago and adjusted accordingly. I rotate between 2 stroke and the Amsoil Diesel concentrate fuel treatment. I purchase fuel from the same place about 90% of the time. Now as far as quality of the fuel not real sure on that.

Do you have a brake dragging? I did. Any codes?

As of the last break job there was not any breaks dragging. There are no codes on the truck. The last codes that were set was for the TPS. Since replaced that with the Timbo TPS. And as far as what gears on the truck I cant remember if they are 3:55 or 3:73 but at 70 mph the truck is turning 2000 rpms. Im leaning towards injectors but not real sure. Truck has a tendancy to smoke a little when under a load even prior to the power puck.

I checked all the valves about 20,000 miles ago and adjusted accordingly. I rotate between 2 stroke and the Amsoil Diesel concentrate fuel treatment. I purchase fuel from the same place about 90% of the time. Now as far as quality of the fuel not real sure on that. As of the last break job there was not any breaks dragging. There are no codes on the truck. The last codes that were set was for the TPS. Since replaced that with the Timbo TPS. And as far as what gears on the truck I cant remember if they are 3:55 or 3:73 but at 70 mph the truck is turning 2000 rpms. Im leaning towards injectors but not real sure. Truck has a tendancy to smoke a little when under a load even prior to the power puck.

there were no 3.73's for 2nd gen trucks, your rpm's are spot on for 3.55's ide blame the pump more then the injectors, but good news is injectors can be tested for next to nothing.

Im leaning towards injectors but not real sure. Truck has a tendancy to smoke a little when under a load even prior to the power puck.

If they are stockers just replace them. It will be the best $200 you spent (once your get $80-$100 for your stockers). More power and you will know thats its NOT them if you replace and can move forward with the DIAG.