My 3.1L V6 1992 chevy lumina is draining gas like crazy put ten dollars in and it didnt really go much

If you've only got 1 O2 sensor, disconnect the remaining 1. If you've got 1 O2 sensor sending out signal, and the other one isn't very well could be causing the problem. On my 97 chevy suburban, it was gettin horrible gas mileage and performance. I bought it that way, I looked at the O2 sensors, two had burnt wired, one was new and one was old, I disonnected all of them, now it runs WAY better, gets better gas mileage and I didn't have to spend nearly 400 bux for new O2 sensors (if you change one you should change them all). Yours should have 4 O2 sensors, upswept an downswept on each exhaust manifold and by the y-pipe. No signal is better than bad signal...or so I was told and learned

Ok huh funny you say I should have 4 cause I found one that's behind the engine, but following the exhaust can't find one after the catalytic converter anywhere looks like they ran a straight pipe all the way

there should be one on each exhaust manifold (a v6 has 2) but on some of the chevy v6's they only had an o2 sensor on one exhaust manifold which sounds like what you're describing. Either way with missing o2 sensor(s) and only one sending signal, disconnect any remaining o2 sensors as it's confusing your onboard computer. And you should also check your mass airflow sensor