javadave wrote:Heavy carbon buildup on the throttle plates can also cause sticking, may want to check those as well.
Javadave is correct, your problem is most likely carbon buildup inside the throttle body from PCV emissions.
With the engine NOT running simply remove the hardpipes from your TB's and spray some carb cleaner on a rag, and using a large screwdriver carefully wedge open each butterfly and clean the inner TB area as best possible. Sometimes a toothbrush can help as well to get into tight areas. If the buildup is heavy enough and fried/dried in place you may have to spray directly to loosen it, although usually you can scrub it out without a lot of effort with the cleaner-wet rag. Don't hose the whole thing down like a carburetor, you don't want to leave a lot of liquid residue as the cleaner will also remove any paint and ruin plastic in areas it's used.