Hi Mitchi - we have the same year and engine, so I hope to be of some help.

I doubt you need rings. Cross-hatching is obvious on the cylinder walls. Next post, please mention the mileage on the engine/truck.

I noticed with #2 or # 3 on the cylinder head the carbon deposit that was prominent on mine, too. Turns out is was the passageway for the EGR valve, and it was completely packed with carbon. It runs through the cylindr head, and also through the plenum (air intake manifold) and the intake manifold as well.

The gutlessness was likely in the various timing things, but since you have it torn down, give it all a good cleaning. Take the EGR off the plenum and clean out that carbon, too. Clean out the EGR valve, itself, and once clean, give it (the moving valve stem) a drop of oil. Give the device some mouth vacuum and see if it works properly.

It's best to wait for other members to chime in, but likely several small problems have added up to one disappointment. That seems to be the way of these trucks, particularly when they're new to us. Many times, the previous owner drove the last few thousand miles with no service or care.

I have a build thread, it might have some insights you can use, it's called "Roy's Garage" and it will help you with some photos and pointers. There's a lot of non-mechanical stuff, so you'll likely have to scroll through a lot of it to get where you want to go.

This forum is a great life-line for just the kind of thing you're doing. Keep us posted on your findings and actions, and asking questions doesn't mean you're dumb: that simply means you need to know. Many here can help. I hope to be one of them.