what did the exhaust chip do for you? does it give you better mpg and power at all? how much $?
also, the only other thing i could possibly think of is that maybe your losing compressing in your cylinders, making the truck work harder to move, = less mpg. and getting the new injectors helped, but only in the fact you were improving fuel flow into the cylinders through the injectors. that s why you jumped back to 200 miles in a full tank. i had a toyota that had only 66% compression left in the cylinders, = less power, worked harder to move the truck itself. but im not sure on all this, just a thought i guess.... | 
