I had this same issue last fall/winter. Then spring brought warmer temperatures and I forgot about it. Over summer the car ran well and I found some small issues. Economy and performance are way up from when I first had the car.

Then it got cold here.

The same issue is back. The car feels like its hanging onto gear changes too long. Or it feels like the timing is being held back. At high RMP, just before a shift, I can feel surging. Feels like the trans is slipping. Its very, very annoying. the car simply feels "wrong".

The odd thing is that most of the time I can just restart the car and its find. Even if I dont let it warm up much at all. I can get in, fire it up, back out and restart and I usually dont have the issue. If I do not restart, I will 99% of the time. Or if I stomp on it hard, it may then act normal again. But not always doing that and I dont like doing it.

There must be something related to temperature that sticks open/closed. My thought it something that may be vacuum related, hence restarting drops vacuum for enough time to reset it. Or getting the RMP way up sometimes helps.

Really clueless on this one. I just dont want to go through another winter like this. Ideas?

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1991 560 SEL / 185k miles
1992 750il / 17k miles - project car