A week or two ago someone posted a question regarding a 94 850 that would not upshift when cold, but upon shifting to 3rd and back to drive, shifted normally. Had one in the shop this week, same symptoms. No fault codes. Black fluid. Flushed the fluid twice, no change. Cleaned conections at trans ecu and trans conector, no change. Replaced PNP switch. It was the cheapest experiment short of trying solenoids or a new valve body. Car sat overnight, similar temperatures, cold start, upshifts normally. This may not work in all cases, but it's a good starting point. By the way, there was absolutely no reason to suspect the PNP switch. No fault codes, and testing with scan tool revealed correct response to gear selection. Hope this helps.