One thing that hasn't been mentioned yet but you need to add to your list of things to do...... Check the timing! If it's way out of whack you can get a lot of popping and low power. Start with the easy tune-up stuff and work your way up. Be patient and you will have her purring like a kitten in no time. Also, don't start out in first gear unless you have a huge load on the truck. You should be able to start out in second gear.
