My 1997 E39 (523i) has this problem. When I cruise at the highway at over 120kmh at the highest gear (rpm about 2K) and then slow down to a lower speed where the rpm goes down to less than 1.5K without the gear kicking downwards, the car will jerk. Even when I press the accelerator, it will still be jerky until the rpm reaches a higher level, say near 1.8K to 2K. Then Dr Jerk goes away. The car also seems to be reluctant to kick down to a lower gear (from the highest gear) when I need the extra power to pull away. My dealer has changed the cam shaft sensor but problem still persisit. He detected no problem with the vacumn sensor and MAF. Spark plugs look clean and dry. Compression test on all the 6 cylcinders appears to be OK too. The next visit he will try to diagnose the O2 sensor and knock sensor to narrow down the witch hunt. Just wanna check whether anyone here face the same problem.