Recently bought a 1992 Legacy SW and have been in the process of turning this into a driver. First did the brakes, front tires and suspension/alignment. The next item on the list was the engine. An uneven idle and stalling was difficult to diagnose. New plugs were installed as a start. Fuel pump was pulled and a new filter (sock) was installed. The 171k pump was still in good shape, putting out 60psi with return line pinched. The IAC valve was pulled off and cleaned. A new water sensor was installed. Was running better but still had the uneven idle and stalling. I did a better job of cleaning the MAF sensor using alcohol and Q-tips. This seemed to be the big culprit of my problems. In the future the oil will be changed, new valve cover gaskets, and thinking of a new Bosch O2 sensor. The proper Bosch numbers are 13250 (ready fit)/15726 (universal). Other numbers to search for are SG286, 234-3083 (Denso), and 24614. Hope this little tale helps, Steven.