check/replace coolant temp sensor... $20 at advance, make sure the plugs are the same, as there's the rounded square plug, and the square plug...


another thing, cheap, and something handy to have around at all times...

go to lowe's/home depot, get the following

2.5" rubber pipe cap (i think that's the turbo inlet size on a stock SR)
get a air hose MALE end, just the tip.
drill 3/8" hole in center of pipe cap
screw in male hose end
take an empty spray bottle, add 3-4 drops of dish soap, fill with water
hook assembly to an air compressor set at around 20-25psi
use spray bottle to wet up all couplers, vac/boost lines, intake mani gaskets, anything that might have air leaking

do all of the above, it'll be around $25 total, and if neither work, then you'll still have a brand new CTS that you wont have to worry about for a long time, AND you'll have a boost leak tester on hand any time you, or your friends need it.