What is the name of the part that is missing, the hose thing that should be connecting to the case that holds the air filter

 

i found the part number but it loos like mitsubishi doesn't just sell the rear portion of the air inlet duct. you'll have to buy the whole assembly. Part # 1505A955

Or you could get one from a Ralliart. The Ralliart air inlet duct is a one piece assy rather than a 2 piece and it doesn't have a resonator. Part # 1505A305. That number is a little funny though. It say it does not fit ralliart but it says it does. see for yourself. http://www.mitsubishipartswarehouse....air-inlet-duct

probably best if you go to the dealer's parts department and see what they have.

honestly i would try to find some hose or tubing wide and long enough to fill the void. no need to spend upwards of 90 bucks when cheap tubing will fix it. Or just leave it as is. It's not hurting anything.