Hope everyone is doing well!

30k miles into the (used)6mt conversion, my car started showing signs of hesitation after driving thru a very shallow yet 50 Meter long puddle. The car was fully functional 3 hours after driving thru the flooded roads. On my way back home, the car seemed to hesitate when accelerating and sounded like it was either burning rich or simply 1 of the cylinders were misfiring. After reaching home safely I let my car idle for good 10-15 minutes. The car was fully functional without any sings of hesitation or misfire
Two Days after driving thru the flodded street, the same issue occurred so I drove it to the nearest Pepboys to get the OBD codes pulled. Considering its a swapped from Original 5AT to 6MT, I knew i was going to get the basic O2 Sensor codes and such because we decided to gut the pre cats while we were in process of doing the swap. I was hoping to find out exactly which cylinder is misfiring so i could pin point the issue to the coil packs or whatever the case may be. Instead, all signs led to a Bad catalytic converter. I was like okay.. lets go home, jack it up and find out what exactly is going on with the CAT or the o2 Sensors.

Turns out.. the o2 sensor located on the bottom half of the pre-cat closest to the firewall was loose, and the one on the top half of the pre-cat closest to the radiator was loose. Now i wont be able to find out if the Main (3rd) Cat is clogged up or not until tomorrow.. but this is what i found while I was underneath my cars after 2 years.

Does anyone have any ideas on this?? >> There are droplets of Oil (not sure if its transmission or engine, but my best guess is transmission) leaking right in between the plate that is shared with the Engine Block and the Transmission.