2001 cat converter

I 've had p420 code issues for a long time now, since I bought the car. Each time I replace something the light will stay off for a while. Sometimes for months, sometimes for only minutes.
I've had the cat replaced twice with universals. The first time the light stayed off for several months before coming back on. I thought it came back on because of the LIM gasket leaking, so I got that replaced. Which fixed it for only weeks. When I took it back they ran computer tests that said the new cat was clogged, so they replaced it, but the light came back on as I pulled out of the parking lot. After that I replaced both o2 sensors which kept the light off for only a couple days. Now the light is back on. Anyone have ideas on what else may be the problem. Please, any input would be greatly appreciated. Thank you.

Welcome to AF. To tell if the cat is working the temperature at the inlet should be compared to the outlet temp, the outlet should be 100 degrees hotter. P0420 can be a tough diagnosis, many other things can cause this. Do a site and google search for this code, lots of info out there. .BTW the cats were warranted for 7/70 or 8/80 on these cars.

Whose brand of gas are you buyin? If it's Arco/safeway/costco, haze yourself.

Well, it's 106k, so any warranty it might of had is gone. One of the mechanics I took my car to said that maybe a factory converter (instead of the universal) would fix it. Does that sound plausable to anyone?