You know, I was kinda wondering if it may have something to do with the EGR... Would it matter which vacuum line to plug? Are you guys talking about the ones going to the modulator or to the EGR itself? I remember checking the routing of the lines and they looked fine. What could be wrong with the EGR? Holes in the diafragm?

I don't know if it matters, but I attempted to clean out the intake plenum with TB cleaner, and must have got a bunch on the inside of the TPS (hence it's replacement). Is it possible I could have done some damage to the EGR by spraying the cleaner directly in the plenum while it was still on the vehicle? Hmmm... I'll check it out after work tomorrow...