Solidjake - do you think I should still run a bottle of chevron techron even if the problem seems to be fixed? Thanks for the info. This was the first time my car has been in the shop for something I didn't attempt to fix since it passed its 50k warranty mark. The mechanic just fixed the brake booster hose as well as my vacuum leak.
dmax - you did guess intake leak as one possible diagnosis. I am going to update my suspension woes in the other thread!
Amazingly, the car now runs quieter. At idle, I can hardly tell the motor is on. The car also hesitates less when accelerating. Previously, the noise of the motor seemed normal to me and I have forever been used to German cars having inconsistent power bands. It is amazing how something as little as a rubber plug on the intake manifold (driver side under the cabin microfilter area) can cause a motor to run so poorly. What is odd is that my mpg's have been good - getting around 400 miles per tank.