Slight stumble with possible backfire

Confused is the word that comes to mind right now to describe how I am feeling.

I decided to do plugs and wires on my truck listed above. Should be an easy job, right? Wrong. I did the plugs and wires. I used the E3 Diamond Fire spark plugs and a good set of plug wires. While installing the wires, I noticed that the distributor cap was loose on one side. I have had the truck for a year, and in that time have not changed the plugs and wires. Strange, because that is usually one of the first things I do. The truck has 82,000 miles on it. The loose distributor cap was caused by only having one bolt holding the cap down, plus a zip tie on the other side. There was a broken bolt on the side with the zip tie. So, I removed the distributor, drilled out the broken screw, and reinstalled the distributor along with a new cap and rotor. The truck fires up, runs fairly smooth at idle.

When you drive the truck, it seems under very light throttle (while in motion) or when decelerating, it "surges" and may be backfiring just a little bit. But if you get on the throttle, it seems fine. Under powered, but fine.

I need help to solve this problem because I need to take this truck on a road trip this coming weekend. Ideas?