Engine light-lean mixture

Went to get a sticker from my local shop, engine light on. Looks to be a lean mixture problem, air leak says the mechanic. He pointed out a "plastic box" (pictured) that he says may possibly have a leak, Problem: when he takes the hose of from the Fuel Injection Pressure Regulator there is no vacuum there. He said the box is probably cracked along the seam, he says he has heard that is common.
I know these guys and they are trying to help me out, so he said see if you can find one and I'll see what I can come up with on my end. I got home and pulled it out (I wish he had) It came out easy enough and says "RESONATOR >PA6-GF30<" on it, but I a search finds nothing (so far) It does look possible that there is a split along the seam, but can't be sure. So I'm looking for the name of this thing, and bring to think of possible ways to patch the seam to see if it will make a difference. Any ideas help is appreciated.

 

Is it actually cracked? Have you confirmed that air is pulling in through the seam? There shouldn't be much of any vacuum coming from that box to the pressure regulator.

 

There is a seam that separates the top and bottom, it looks like it has shrunk/distorted slightly over time, change it may leak. The mechanic said he sprayed brake cleaner around it which gave him the idea of the leak (he didn't say if it rev'd up when he did it, I didn't ask) I cleaned around it with alcohol and the applied some black silicon along the seem and re-installed. It idled much better then before, I'll give it a couple of days in hopes the engine light goes out. Meanwhile I found one on eBay and will swap it out when it comes.