erractic rev. PLEASE HELP URGENTLY on 1999 BMW 328i

hi, i have a 328i e46. while driving the rev falls and then picks up and falls again esp when i leave the accelerator and then press it again. At the sam time there is a noise from the back of the car. no one can tell me what the problem is not even the agents. Please help

Asked by for the 1999 BMW 328i
This needs to be looked at by a competent shop, one who will diagnose the problem. It's impossible to do that without seeing the vehicle. Can you take it somewhere else? Is there a BMW Dealership near you?
1 more answer
you might want to check the idle control valve