Trying to track this down but for some reason someone stuck a screw inside this rubber hose but I can't track down where it plugs into.

It's the KV6 engine.

 

I believe that is part of the crankcase emission system (PCV). See pages 28 - 31 of 363 in the workshop systems manaul, part of the RAVE.

 

Someone replaced the original elbow with a "T" and then added a short length of hose and a plug to seal it. Probably didn't have an elbow in the junk drawer. The hose pulls air across the fuel injectors to help atomize the fuel. This was the last year this type of fuel injector was used, with 2003 having the more conventional system.