EEVEE

Hello. Im quite positive my cat is going bad because *after* hitting a small puddle that came up to my door i soaked the entire engine bay, and it cut out on me and soaked the distributor in the process so after sitting for about 20 mins for it to dry out i could start it back up. Anyways after all my errands were done i came back home and turned my jeep off with the door open and noticed a little tinking sound when shutting my engine off. I thought it was maybe my loose exhaust clamp because that is dangling around underneath. But i tried again with the same result and my jeep was NOT happy after its bath in a puddle because i noticed the revs were hanging quite badly after. But after sitting overnight and trying it again it is fine now. It randomly happens after raining. How would i test my cat to find out if its going bad? and if it is can i just bypass it for the time being till i can get a new one? meaning pulling it out and running a pipe in its place? My jeep is a 99 with 203k miles and is still the original cat. I notice im getting pretty crappy gas mileage too.