I wish I knew more here but I am helping a friend with a problem on his 90 740. He was driving and came to a quick stop and when he started again the engine started running very poorly, and the car would not really rev higher than 1200 rpm. It has been described to me as a boom boom noise when the engine is reved. He took the car to a shop which did extensive testing and so far has not been able to pin point the problem. all the sensors seem to be fine AMM fine etc. THe car runs fine at idle but wont really go faster than 1200 rpm.. The mechanic told me it seems like there is a rev limiter or something. Unfortuantely, I have not actually had a chance to look at the car myself yet, but based on this information is there any suggestions anyone can give?? I guess the only thing left causing this kind of problem is the ECU? I looked a little in the FAQ and there was somthing about a failing module having a symptom of "the engine will not rev above 3000 rpm" so that seems to apply to a certain extent.

Thanks for any help you can give!