7.3 horrible mileage torque converter??

[jjrustad]

I recently bought a 2000 f250 with 7.3. I have only put about 1000 miles on it and I get between 8 and 11 mpg. The problem that I have had is that sometimes at diffent speeds the truck will start to shake. it gets worse and soon gets real bad . It will do this for a few miles and then it suddenly goes away and its like I have a sudden boost of power. The truck seems to run fine and the tach does not change. I have downshifted when it does this and the tranny seems to shift right. The one thing that I have noticed lately is that when I let off of the accelarator, no matter how fast that I'm going, it always seems like the truck doesnt want to coast, almost like the front axel is engaged, which it is not. The truck has 140,000 on it. The truck kind of acts like it is underload when the shaking starts. Its my first diesel and its getting pretty frustrating, especially at the price of fuel. Please help before I go back to gas engines.

[chrispaine]

dont know but I would like to know what you figure out.