Has anyone had a problem with the Drivers Information Center Average Fuel Economy being way off? Has anyone found a cause.

I use to see high 16 mpg on the DIC all the time when I was getting low 15 mpg consistantly calculating by miles driven vs gallons pumped. Lately, the DIC is telling me I'm getting 19+ all the way up to 23 mpg when I'm actually averaging 14.5 to 15 mpg. I have to say something is not as it use to be. I've been wondering about injectors but the balance rates have been off ever since I purchased the truck 70K ago and have not changed much.

With a couple other threads saying 4+ will cause smoke, my truck never smokes and the balance rates on some cylinders are in excess of 4. The only issue I had was a surging and a new fuel pressure regulator fixed that right after I purchased the truck.

I do have some EGR codes that I have not fixed. P0401, P0404, P1404 P2365 I think is the last one. EGR Open, Closed, Insufficient Flow, and a I think it is a Turbo Vane Position Sensor Code but it has more to do with the electrics. I am also thinking the EGR and EGR cooler are plugged with carbon and if it has gotten far enough in the exhaust, maybe it is restricting the turbo vanes from moving correctly which I guess could be causing my fuel economy reduction. I can't imagine it is playing a part in the DIC Average Fuel Economy calculation. Other thoughts?

I just checked the balance rates tonight and here is where they are. I did not drive it to get it good and hot.

ECT 91F ECT 91F ECT 120F
Park In Gear In Gear
#1 -1.7 -2.0 -1.5
#2 0.3 -0.2 0.2
#3 4.6 5.1 4.9
#4 0.2 -0.1 0.3
#5 4.2 4.0 5.3
#6 -3.9 -3.6 -3.5
#7 0.6 0.8 0.3
#8 -3.9 -4.1 -5.8

I'm sure many will tell me that I need the injectors replaced but I can't believe this. I have no smoke, the truck starts and runs great. Maybe a set of injectors would be good but the cost, it will have to wait.

Feedback is welcome. Once I can put this truck down for a week or two, I'll dig into it to find out what is going on but right now, it is getting me to and from work. Not exactly an econobox but a little cheaper than buying another car.

Thanks
Steve