Did it ever run correctly after you did all the maintenance that you listed?
Did it run like crap before you started all this maintenance?
The initial reasoning for the maintenance that I have done so far was because of the flexplate being cracked but I didn't fix it and I continued to run it with the flex plate issue, see attached images, for about 2 months I ran it. During those two months it progressively got worse, some of the codes that pulled through the AutoZone scanner in those two months were O2 sensor bank 1 and knock sensor. After getting the flex plate and new starter put in it ran good for half a day. Next day, it was shaking and smoking a little bit. Because of that and because I waited so long already to get the work at that point done I stopped using it and bought the knock sensors for it, a full tune up minus a fuel filter because I forgot to get that, the intake manifold gasket because to get to the knock sensor is you have to take off the intake manifold. First two or three days after fixing the knock sensors, again see attached images, it ran like a charm. The only code that came up was my radiator fan relay circuit issue which now I've replaced all three relays and that issue is starting to get under control but after a couple of days it started shaking at idle heavily and smoking like a train. But it only shakes aggressively if I start it on a hill with low gas, or after it's been running for a few hours. It's so hard to describe 50% of the time it runs fine but then the other 50% it almost seems like the engine is about to die. But to round up that lengthy explanation, it ran perfect when I bought it at $214,000 mi now it's at 220,000 miles and I ran it for a little over a thousand miles the flex plate problem was occurring and I think the flex plate issue may have caused these other issues to pop up or the fact that it's just that old of an engine and all these parts that I'm replacing are original. It's hard to describe, but whenever it smokes it reeks of gasoline not burning oil. Any theories? Thinking it has something to do with the fuel delivery possibly a fuel pump, I also saw one recommendation from somebody on another website that said to check the catalytic converter but that's one of the most expensive options it could be so I hope it's not but the person who recommended that to me also said that the broken flex plate issue that I was having might have been the catalytic converter but as soon as I fixed the flex plate that issue stopped but not before these other issues started because my theory is that I ran it too long with that issue and it caused damage elsewhere, or if I'm lucky maybe it's just the fuel filter is clogged. Any theories?
For reference, the picture of the knock sensors; far left is original not corroded and middle is original rear that was corroded and far Right is the new one that I installed and yes I installed both front and rear just to get it all done at once while it was open. And the second image is the broken flex plate that I was running for a little over a thousand miles. The idle shake and serious smoking issue didn't start until about 7 to 800 miles running it with the broken flex plate. My friend who helped me install the knocks on series has the same vehicle and worked on it for four or five years he thinks that possibly it could be a valve or timing issue worst case scenario.