Chevyidaho

I bought this truck in early December last year. It's been a great truck and I really love it. It has some major issues though and has since I bought it. The previous owner told me he fixed certain things on it and if he did, I'm pretty sure he had no idea what he was doing. To start off, he didn't know how to weld. The ground wire on the starter was welded on and came loose so I had to buy a bolt to fix that issue, then somebody tack welded a cherry bomb glasspack on the exhaust and completely cut off the cat. The main issue is the misfire. When I bought the truck, the check engine light was on. Truck seemed to run, sound, and drive okay so I assumed it was probably something minor and didnt think much of it. That was my biggest mistake! I finally plugged a code reader into out only yo get a p0305 cylinder 5 misfire code. I work at a shop and had another tech help me with a compression test and the cylinder has compression just not as much as it should. When I bought the truck, it was idling at 1100rpms and it's now down to about 850rpms in park. I'm trying to figure out what is causing the misfire. In the mornings after the truck has been sitting, it'll also take a few seconds to start. It'll crank a bit and sometimes take at least 30 seconds of more before actually starting. I think it's just a slight misfire from the data I was getting on the computer portion of the code reader at work. There is also history of a p0300 random multiple cylinder misfire. I've had to have that one cleared twice. The check engine light stays off 98% of the time, but the misfire is still there. If I plug a code reader in even without the check engine light on, I still get the active p0305 code and the history of the p0300 code. Every once in awhile the check engine light will come on for maybe an hour or two then go back off for several weeks. So my question is, what could be causing this? The wires are new, and I've reached the spark plugs because the ones that were in when I bought the truck were autolites. I put in some NGK plugs in November and today decided I wanted to install AcDelco it's instead so I did. There was a decent amount of oil on each other plugs when I took them out, some more than others. All of them had black soot stuff on the end. Also, the previous owner claimed to have replaced the distributor and rotor. The rotor looks original. He did replace the cap. Is it possible that the timing is off? The distributor was taken out, cleaned, and the engine retimed but I believe it's possibly not timed all the way to where it should be. Should I try replacing the cap and or rotor and see if it solves my misfire issue? I'm to the point where I don't wanna keep fixing it and pouring money into it when I could just get another truck that runs better. Any info would be greatly appreciated!