i agree with this, seafoam does wonders. put half a can through your pcv line and itll probably cure it. search about seafoaming of you dont know what it is.I tried to do some research for you. I have a single port so I know very little. from what I found, it looks like you need to clean your IMRC. It gets gummed up just like the upper intake manifold that we all have to deal with using Seafoam treatments. There appears to be linkage just like a throttle body and a controller to open and close them.
That's all I could decipher. I would think that that indicates a serious Seafoam treatment is needed no matter what.
I'll check back to see how you fix it. Good luck with it. Sorry I wasn't more help.
Since it's before the TB, I don't think there will be enough vacuum to get it sucked up easily. Just use the PCV line that runs between the upper intake and valve cover on the drivers side. Pop the end out of the valve cover while the engine is running and let the hose slowly suck up the Seafoam (don't just dunk it in or the engine will stall).I got a bottle of seafoam. Im goin to do it in a few minutes, Would it work to put it in the vaccum hose that plugs into the Air intake hose and goes straight to the itake manifold?