TERRIBLE mpg, low power...HELP!

[dragracer3346]

Hey guys, new to powerstroke.org and really looking for some help. My truck has been getting worse and worse fuel mileage recently. I'm down to 9.7 mpg last time I filled up, and its looking even worse for this tank. Before I bought my current truck, I had an early 99 that was all stock except the 5" exhaust and it had gobs of power. This truck just does not seem to have the power the old truck had. The truck will definitely get up and go with the programmer, but on stock it just seems extremely sluggish. I have checked some things other people have had trouble with like sticky calipers etc, and nothing obvious was wrong. This truck is also different than my 99 in that the transmission shifts what I think is too soon and really lugs the motor. When I accelerate hard, instead of holding a gear out longer it will upshift and lug the motor until it eventually pulls the rpm's up. Whether these issues are related i'm not sure but thats what I'm really hoping you guys can help me out here. The only thing I can really come up with is possible a bad/weak turbo because I know the 99 had a new turbo and I can really tell a difference in sound. Thanks in advance for the much needed help!