If plugs and wires have never been changed I would change them. You're going to have to pull the upper intake off of the engine to change the wires so while you're at it I would also change the coils just to be safe. The cheap coils from eBay work just fine in my experience. You'll need 2. discovery 2 coil | eBay

As far as spark plugs, I personally like NGK. Some people stay stick with Champion and those work just fine. Others say go with the Bosch Platinum and those people don't know how bad Bosch spark plugs are. Frankly, even whatever the store brand is are probably fine, but NGK is just my preference. I've used them for years all the way back to changing spark plugs as a kid with my grandfather and they've never caused me a lick of trouble.

Wires, there are several options. I forget which brand is cheapest but the 8mm plug wires are best. They won't fit back in the factory holders on the side of the valve covers, though. You'll have to zip tie them together and off of the exhaust manifolds.

 

Is there a good video/pictures for changing coils and wires? And while we're at it, how do I take off the upper intake?

Pretty sure I can figure out the spark plugs.

 

Let the fun begin (Intake Removal) >>

 

I think the only direct-fit aftermarket, emission compliant complete y-pipe is the Magnaflow... and its only for the 2003

 

I sniffed out a bad wire 1 time; didn't have any codes but the truck would hesitate under load espc' right before shifting to 4th gear. I went & started pulling spark-plug wires & 1 of them just came apart at the boot end that snaps onto the plug. Replacing wires is a big job because the upper intake manifolds have to be removed & very inclusive. Some replace the coil packs simultaneously due to the effort involved. There is a good chance you have a faulty wire but its just so difficult to swap wires around & check if misfire code follows to dift' cylinder, know what I mean?

 

for federal emissions, all the magnaflow y pipes are compliant. Hell they all use the same y pipe. You can even check rock auto if you don't want magnaflow. I just went with them personally BC I have had better experience with their cats compared to other manufacturers.