Don't know if this applies, but I owned an 87 3 series that shifted fine until one day when I had the car in for service. The techs changed the transmission fluid and as soon as I left the facility, I had problems mainly getting into 1st gear, and also difficult shifting. I kept the car for a week, thinking that it would get better with use. It didn't, and when I took it back into the dealer, they replaced the fluid with the same type I had before. The service adviser said that the new fluid they used was thicker and the cold temperatures probably caused the difficult shifting. With the original type of fluid replaced, the shifting problems were gone.