I recently put a straight pipe on my 95 3RZ Tacoma, just for fun, and noticed right away it's running real rich. Both O2 sensors are correctly connected, and after resetting the ECU the check engine light came on within 200 miles. I am thinking I have a bad O2 sensor, so I am wondering if I replace the bad sensor(s) and reset the ECU again will it adjust the fuel:air ratio so it won't be running so rich?
I will be putting a new cat and cat back on soon, so I'm thinking I'd like to get the fuel-air ratio straightened out before I make the truck legal again...

There is also a very noticeable increase in overall torque and horsepower, but that thing puts up the loudest racket I've ever heard

Thank you for your time.

Pull the codes before you waste any money. Without a cat, you will throw a rear sensor code.