Silver01Bullet

My 2001 XJ has been getting a tick recently, sounds like a lifter or rocker tick. Have been doing some troubleshooting, in the process of this I cleared an old code P0303 that I thought I had fixed by replacing the spark plugs, coil rail, and Crank position sensor about a year ago. At that time I cleared the code, and at some point it came back on. This past weekend after clearing that code, almost immediately on the way home, it started running really poorly, shaking, bucking, losing power... like in a limp mode. It died on the way home, in traffic, I got it to start and limped it to a parking lot, still shaking, bucking, and almost no power, and it died and would not start, cranking VERY slowly. I got it towed home, put a scan on it today and got P0300, P0301, and P0305 codes. The most common fixes seem to be most of what I have already replaced. I'm wondering why it would do this after clearing a code that has been showing for a year?
Any thoughts would be appreciated. I'm not going to put much into it as we have already bought a newer vehicle.
So, in one way shape or form this Jeep will be gone, but if I can have a relatively simple/inexpensive fix, I'll try it. Would be a lot easier to get rid of a runner.