My cousin'* GTP. Says he hears a big vacuum/pressure leak somewhere, but can't figure out where. Any pointers as to where this could be?

Can you verify that code? I don't see a P4201. As for a vacuum leak, start spraying carb cleaner around and listen for changes in RPM

I'm thinking 0421 ... but not looking it up until it'* confirmed.

Meanwhile, like Dan says...if he hears a leak, then find the leak, fix the leak.

A p421 would fall in to the EVAP area. Those are a pain to find

Code is actually p0401, Exhuast Gas Recirculation Flow Insufficient detected

Btw, Hi guys, I'm Jason-Xtreme'* cousin.

I'm assuming its got something to do with this missing tube. See there'* a little nipple sticking out under this black thingy ma bobber in the engine and it looks like there "should" be a tube that goes on it. However there isnt, and Im stuck trying to figure out what in the world went there or what tube/hose should be connected to it. Any help would be greatly appreciated.

Nothing missing there, it'* just a vent

Really? It looks rather peculiar sticking out like that. Hm, well then Im really hoping the error is being caused by the small crack in tube right above it. A few of those tubings in there are somewhat old and were electrical taped together by the previous owner, however I retaped them temporarily and its still chugging a bit. Any idea as to what else would cause this error?
I figure since its "recirculation" its gotta be one of the small tubes in that area, if not that peculiar looking exhuast hole.

That is your boost control, not the EGR. If the hoses are old and cracked, replace them. But. The error is the EGR, that'* on the rear side of the throttle body. Could be a stuck valve.

Hopefully there'* a crack in one of the tubes coming out of the EGR valve that I'm not seeing. I suppose I find out tomorrow when I replace them all. It'* not too significant of a problem but its definitely noticeable as you can hear air leakage on that side and you can kind of feel it in the lower rpm performance.

The EGR does not have vacuum lines. It has a metal tube that comes off the rear exhaust manifold. Goes to the valve with a solenoid on top of it, then another metal tube goes from that valve to the lower intake manifold right under the throttle body. These do crack, and the only way to check them is to remove it and hold it up to the light. When they crack the idle will be real rough, almost like when you have a big cam.