Rough running (almost stall) when cold in Park
I'm new to the group, so please forgive me if my question sounds naive. My mechanical experiece is primarily with Porsche and VW, but I did spend several years in the shop of an Oldsmobile dealer. Quite a few of my friends and neighbors now own Ford products, and I must admit Ford is my favorite American make. I'm often presented with questions and requests for mechanical help--and that's the reason for this message. My neighbor called me yesterday to say that he's experiencing a problem with his 1991 Taurus. According to him, the car, when cold, runs roughly and almost stalls in [B]PARK. Move the lever to DRIVE, however, and he says it all becomes smooth again. Move the lever to PARK, and once again the car runs roughly. This scenario contines until the engine is thoroughly warm. At that point engine running is normal in all quandrant selections including PARK. What the....could be causing this? Is there any vacuum device that could be leaking under the described circumstances? Any suggestions would be welcome before I dig in on a wild goose chase. Thanks.