the headers connector to primary cat is gone..

[Shaddyy]

i had recently just found out that that part is gone, dont know if it was there before or something happened to it. i checked eariler today under the car and was confused.
http://prntscr.com/l64d9v
thats what it looks like, i dont know the name of it.
and my car just went into limp mode earlier today too, saying all the cylinders are misfired 1-8. i have no idea whats going on tbh
oh and when i start the car, it idles rough and idling around 400rpm - 600rpm.
when i hit the gas it takes about 2-3 seconds for the car to start driving.
after driving, at a complete stop, the car idles back down to 400rpm - 600rpm and i can feel the car jitter