Cool - thanks for the detailed explanation.
On the LE5, removing the intake manifold is a 15 minute process. Not sure about the LNF. If the rain ever stops, I'll go ahead and yank it off. I found a video from one of the Cobalt SS guys showing the cleaning process, and it looks pretty straightforward.
In the mean time, I ordered a cheap bore scope (really "needed" one, anyway). I'll check the accessible valves through the vacuum port on the manifold. With 100k miles, I'm sure it's going to look pretty terrible.
The real question is if this will impact the misfire issue. The TSB implies that it will, and it's worth taking care of in any case. Fingers crossed.
Blue-ish 2006 2.4, Werks stage 1 turbo, Borla cat-back, DDM braces, Spec aluminum flywheel, Spec stage 2 clutch, Werks aluminum radiator, some gauges, RKSport hood, Morimoto FX-Rs, GReddy Profec, Norm's fenders
'07 GXP, RPM Stage 2, Solocatless downpipe, TCE Wilwood 6 piston front brakes, 4-piston rears , Stainless brake lines, slotted/drilled rotors, BC Racing BR coilovers, Performance Autowerks intercooler, DDMWorks CAI, charge pipes and braces