1992 dodge spirit 2.5L engine running rich

i have had this problem for a few years as a matter of fact. i have replaced the O2 sensor countless times and i was told things like a vacuum
leak could send false readings to the map sensor which would directly affect the O2 sensor, a bad CTS would screw it up and even possibly a bad fuel injector. i've tried replacing the vacuum lines, the map sensor, and fuel injector and it still does the same shit. i don't think the CTS is the problem because when i scanned it, it wasn't wiggin out. but here's the clincher, it doesn't run crappy constantly, just on and off and it starts doing so a little while after it goes into closed loop so im basically stumped. can u guys clarify what could possibly be goin on with my piss poor excuse for a car?
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