It sounds like you are going to rack up a lot of hard miles on your truck so the verdict goes to a diesel type ending which among other things you will pay a little more for gas but in the end get better gas mileage. You can get a little more detail at this site to really get a good synopsis of the benefits of the two check here http://www.trucktrend.com/features/tech/163_0210_diesel_vs_gas/index.html. As for Ford or Chevy, well that is an age old battle that may never have the correct answer, however I do like the increased fuel economy of their gas trucks and the perceived "green" that is ecologically conscious way they have been re-branding themselves lately. So, In the end my recommendation would be a Ford diesel type truck. I hope this helps and good luck.

The steering stabilizer helps prevent your car from wandering all over the road at high speeds. The wobble on your car is typically from the excessive shaft play in the steering box, so its mainly a precaution.

Performance parts usually do not help fuel mileage. A cold air intake can help a little bit, but make sure to keep the oxygen sensor clean as some filters can dirty it. You could also look into purchasing a Banks performance kit if it is available for your truck.