wow how is your car not getting a cell with an o2 unplugged?

how is it made for your 97 accord if it doesnt have an o2 bung?

what brand cat is it? is it a high flow cat you got off ebay? if your state has emissions testing, a no name high flow cat will most likely fail.

with the o2 disconnected i bet he's running richer than normal, gas mileage will go to hell, so yes it will run like shit, not complete uter shit but shittier than normal.

if his car is modded like many of us, even simple little mods like i/h/e an adjustable FPR, fuel rail, and maybe timing advanced, those preprogrammed fuel maps wont work so good.

you need something like... with an O2 bung