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I just reconnected the big hose but when I was wondering if anyone knows why the previous owner would have capped this line and left the big one that goes to the front most(near front bumper) valve cover hanging. The car seems to run fine both ways.

After doing some research I think I have what might be the answer. I think it's part of the PCV system since the other side goes to the other valve cover. The only reason I could find to leave it disconnected (which should never be done without at least a filter) is if excessive blowby is getting into the engine. I don't know how one would be able to tell this but from what I read apparently a catch can is a better solution then a filter or leaving it open.

It's indeed connected between the front and rear valve cover.

Front blows, rear sucks.
The other end of the T normally leads to the airfilter box/hose.

Not sure why it needs to be connected to the airfilter side.

It's sole purpose is to breathe engine fumes back into the intake for emissions

you're right but you can advert this hose with a vent filter easily