i almost had to do the same thing on my girlfriends grand prix luckly is wasnt that and we still havent found the problem but she said her gas pedel was sticking so we cleaned her trottle body and it looked worse then your is was nasty it took my dad forever to clean it out luckly my dads neighbor is a gm mechanic at a local pontiac dealership so we had him look that the intake for us and it turned out to be fine. but wow what a mess u had. hopefully its the only time u have to do that.
1999 Pontiac Bonneville SLE 80,000 miles
Mods: Silverstar low beams, Kenwood MP-828, JBL 6x9, Polk 5 1/4 comps, 2 JBL 12 in subs, 900w Rockford Fosgate Amp, Flowmaster 80, CyberWhite Fog Lights.