Okay, I just got new injectors put in my car in the quest for better mileage.

They haven't helped, really...

Anyways, the guy who did my work took off the line that goes from the throttle body to the passenger side valve cover (the CCV) and just plugged the connection at the throttle body. Now, should I just leave it like this and get a breather for the valvecover, or should I buy a whole new line, and get a new piece for the valvecover and run it to the throttle body?

Also, on the bottom of the MAF, what are those two holes (on the side, on that boxy thing)

 

That would be "PCV", or, Positive Crankcase Ventilation. It's purpose is to draw a slight vacuum on the crankcase. This has two effects: First, it pulls any blowby from the cylinders back into the intake, and helps reduce oil contamination. Second, it helps the piston rings seal better. I would put the system back together, so it works as intended.

 

So, it is the PCV, just minus the PCV valve?

Do I have to get the whole hard-formed line that was in place before, or can I get a rubber line to run from the throttle body to the thing that goes in the grommet?

This doesn't have anything to do with EGR, right?

 

the part your talking about is the breather side of the PCV system, the PCV valve is on the other valve cover.
regular rubber hose will work, but over time it will swell & get soft from the oil fumes.
if the rubber fitting on the TB end of the plastic hose is all thats bad, you can use a short piece of rubber hose which is better than a long rubber hose.

no, it doesn't have anything to do with the EGR.

"Also, on the bottom of the MAF, what are those two holes (on the side, on that boxy thing)"
if its the holes im thinking about, they are threaded & are for mounting the MAF to a bracket on

 

I figured it was for a bracket.

Back to the PCV system.

The whole hard line was removed, so, the throttle body end is just capped. I would need a new 90* that goes in the grommet, and a new line to the throttle body.

 

You could prolly find one at a junk yard, or, buy new from the dealer. (longshot...) GM hasn't produced a TPI car for a while, but, some parts may still be available. Probably would not hurt to check with the local parts stores either.