HI, I have a 1992 960 wagon. I had been postponing the replacement of a gear-position-sensor (or PNP switch)that had been acting up for about 6-months. About 2-weeks ago, the car failed to start, so I decided it was time to tackle the task. During this time, I also performed the following repairs:

a. replaced the radiator (replaced w/ Nissens type; old radiator had cracked plastic tanks)

b. replaced radiator hoses

c. replaced thermostat

d. replaced gear-position-sensor or PNP switch.

After these repairs, the car would vibrate on occasions at about 2,000 rpm and in 3rd gear. This "vibration" would most often (but not always) occur when the car was under a slight load (i.e. traveling up hill, w/ AC on). I felt fairly confident it was a transmission related problem because I could shift the car to neutral during these periods and the "vibration" would stop. The best way I know to describe this "vibration" is sort of a "stumbling" almost as if I had time periods of trash being in the fuel filter (although the tach stays at constant rpm's). Furthermore, while idling, the idle is sort of low (600-700 rpm) and "stumbles" a bit.

With these symptons in mind, I thought I may had knocked loose some sludge or something while replacing PNP and decided to replace trans filter, trans fluid and perform a flush. I performed a super thorough flush using about 5 extra quarts of Havoline Mercon Dexron III. Also, I cleaned the electrical connectors on lower driver's side of trans and used dielectric grease to re-install connectors.

I have driven the car a couple of times; trans level is correct. This problem still persists (note: the tach stays at constant rpm's during these periods except the idle stumbling I described). Is there a loose vacuum hose somewhere - I haven't been able to find one. I'm stumped. Any advice would be greatly appreciated.