A couple of days ago, I noticed my trans looked like it was covered with oil and thought that it already sprung a leak after rebuilding it almost a year ago. But it turned out that it wasn't trans fluid. Several weeks ago, I did a Seafoam treatment with the spray can version, including shooting it up on the IACV. Well it turns out that some of it that didn't make it through the engine ended up in the resonator part of the intake tube and started to come out of the sealed part of it. So there was a vacuum leak that I would have never thought of checking.



I shaked it around and there's still some inside, so I went to the local yard and got another one ($6, hooray for 1/2 off sale), checked for leaks and replaced it. So far, a hesitation that I would encounter once in a while hasn't come back so that's good.

I got a question though. Anyone know the name of this piece that goes in between the intake tube and MAF? You can see from mine it's starting to break apart and the others at the yard were about the same condition. I tried looking online, but not knowing the name, I cant find it. Nissan doesn't show this piece on the parts catalog either.

 

i pulled mine and cleaned that seam and ran a thick bead of black rtv silicon i had left over all around it,just in case,and inspected the flex duct and the seal you have pictured
thanks,nice find!