Trihull, it's scary how absolutely similar our cars and problems are! Holy cow! I also have a 92 Lumina 3.1, and I've just recently been having problems with the car sputtering or dying when idling (going down a long hill, stopping at a stop light, etc.). I also have had a horrible squeaking noise in the back for years now. It gets so much worse when the weather is hot and dry. I noticed that the noise is actually coming from where the two bars that connect between the rear tires meet. A buddy and I tried putting some grease in this area, but it only helped for about a month and went back to squeaking again. Let me know if you find out exactly what it takes to fix that.
And as for my running rough / dying problem, I noticed that my IAT somehow got unplugged, so I think that may have something to do with it. Otherwise, I'm going to look into the IAC and the TPS. Glad you got your problem fixed!