That little hose under the throttle body caused me about a day of head scratching wondering what we did wrong when I put new heads on my truck... truck would run good down the road, but idled like crap, reving, then almost die, over and over. I kept hearing a vacuum leak and found it had pretty much dry rotted in half from where it goes near the exhaust.... I just found a new piece of rubber gas line (because the original had that printed on it) and runs like it should now.
Oh yeah, I cleaned every bit of my intake while it was all apart, you should see how gunked up they get down in the ports near the intake valves. Had to use paint stripper to get all the crap out of the ports, didn't seem to damage it at all, but that is the only place I used it, the rest used the regular throttle body cleaner, whatever kind walmart had.