Cleaning Intake Manifold

I'm having to replace an engine on a 1999 silverado with a Jasper remanufactured unit. To keep the warranty valid you are supposed to thourghly clean the intake manifold of all carbon build up. Does anyone have any tricks to cleaning the carbon build up out of the inside on a plastic intake?

believe it or not i tend to use brake cleaner for stuff like like the stuff i use is under nice presure and cleans very good, then evaporates..try it.

Let it sit in antifreeze overnight or longer. When I used to build diesels I would put the pistons in a pan of the antifreeze that came out of the engine and the next day the ring grooves where a breeze to clean.