yep, a lot of gunk builds up in the intakes of this engine.
If you want a long term solution ... remove the oil breather pipe from under the throttle body, along with the breather from the front rocker cover that goes into the intake.... and run them to a catch tank.
You can also use seafoam in your oil. I've recently removed several sumps and i can recommend cleaning the sump and valve covers before using seafoam in your oil.... otherwise you might just transport carbon/coke deposits to the fine oilways that lubricate the cam. followers and chain tensioners.... G.