My '07 is real sluggish and always having to go into passing gear to get it

What is your question?

moving. A couple of times it would all of the sudden start pulling real good. When I first start it and take off it runs a whole lot better then it go's into snall mode ! I get terrible gas milage also. I had a 2006 5.3 that was twice as fast. I'm not looking for a race truck it's the heavy laboring to get it to go and I know it can run better. Mic says no codes and it's ok.