OK so the last 3 days, I noticed my 05' neon 2.0 sohc N/A daily driver was pinging, under very light throttle at first, could barely even hear it. Figured, no big deal, probably bad batch of gas or something. Well, yesterday it got much worse, much louder pinging and under most forms of acceleration. Well today, the crap hit the fan I guess. I drove to lowes, same symptoms as yesterday, but when I started it up at lowes to leave, it was seemingly only running on 3 cylinders at idle, fairly rough idle, and pinged BADLY on any acceleration. Limped it home, checked the codes. P0304, which is cylinder 4 misfire. So I pulled the spark plugs, they all looked fine mixture wise (black rim around the base of threads, porcelain just slightly discolored but mostly white) except cylinder 4 had molten speckles of aluminum on it. So, I did a compression check. From 4 to 1, 85/105/145/155. Now this was engine cold, holding WOT, but thats still pretty bad on 3-4. Friend of mine suggested I try a trick, pour about a tablespoon of oil down the spark plug hole and see if compression rises and this will tell if the problem is bottom end or top end. So I did that on #4, it bumped compression to 145. So it sounds like perhaps I just have very worn rings. But my question is, I've never seen this cause pinging, especially with a 3 day progressively worse extremely rapid decline. 4 days ago, engine was running like a top zero issues, but I never did a compression check so hard to say what it was then. Just wondering if anyone else has had experience with a similar issue and knows exactly what the problem is. I just find it hard to believe that this is a simple worn rings situation, but perhaps I'm wrong. Now one more thing, if I free rev to about 2k rpm, it makes a funny sound. The best way I can describe it is if you know anything about computer fans its the sound that a fan makes when the bearings are going out and the fan is in imminent death.

Any advice/experience/etc would be appreciated. I don't know much about the 2.0 sohc engine other than it got me 30-34mpg as a daily driver lol.