that is exactly, and I mean exactly what my 1988 325iC did at about 130,000 miles, started noticing it at around 125,000. Almost an impression at first, wasn't sure if I was suffering a siezure or something or if the car was actually doing this. It gradually became more apparent that it wasn't me, there was something with the transmission. This was a ZF 4-HP22 model. Finally, after a trip to Denver from Santa Fe to watch the Cubs play the Rockies the reverse crapped out, forward gears worked OK. Solution, tranny rebuild, the clutch packs were burned and some cool looking aircraft aluminum part (they gave it to me for a momento) that had to do with reverse had excessive play....but, the lurching...ah the lurching...kind of wierd isn't it?