BMW Repair: 94 325is rpm surge/rev, airflow sensor, 325is

Question
Don, I have a 94 325is, auto ,71,000 miles Vin wbabf4324rek11775.At highway speeds making a gradual pass or merging into traffic I get a surge/rev in the rpms.It surges up 1000 rpms for 5 to 6 times than stops surging and car than accelerates normal. Three bmw techs have been in car when this happens and they have never seen it before,do not know what it is.Airflow sensor has been replaced, new plugs, fuel injectors rebuilt. Only does it during speeds 50 thru 70 under graduall acceleration. thanks for your input. Jim

Answer
If the Idle control valve and the throttle plates clean,all hoses soft and pliable not cracked at all I would have to go with mt first thought something I don't normally ever say, if it is acting like it is winding up like a rubber band and acts like it surges,the ecm needs to be replaced.Years ago I had a situation like that had checked everything even had the BMW rep involved and after we had come back from the road test he said that is what it was,I replaced it and it was the ECM.The mapping of the parameters timing,fuel,spark,etc was some how were wrong.