while adding/removing ATF to get the level just right, I noticed something quite strange. When I added more fluid to get it to max level, the engine idle rpm would jump up & down constantly from 450 to 700?? this effect was more prominant when I put the gear in D.

then when i pulled out about a half quart, the RPM fluctuation got a lot better. Am I imagining things here, or is there a reason for this?? obviously i noticed this because when i went for a short drive and waiting at a light, the car would stumble and shake like she was going to stall (never did)

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Current cars:
2001 MB E55 AMG
2003 Honda S2000
2000 Honda CRV

Gone but not forgotten:
2004 BMW 325i 5sp sport
1999 BMW 540i sport
1997 MB E420
1995 BMW M3 coupe