A4 engine revs

My 1994 manual Audi A4 1.8 has just developed a problem - The engine revs at park constantly fluctuate between 1500 rpm and 3500 rpm approx. When i
try to drive the revs rise to to no more than 3500 rpm and then die away to 1500 rpm, meaning i cannot accelerate. This ocurs in each gear. The AA man suspected an air flow meter and/or engine management fault. Has anybody any ideas on the cause of the fault?
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Could be a lot of things....
Might be a sensor problem of some kind. Also could be a vacuum leak. Suggest you start by checking vaccum hoses & looking for splits etc. You might also try cleaning the throttle body. A MAF sensor would be a likely candidate as these do have a habit of failing & would be a good place to start - not the cheapest thing in the word though.
Its less likely that the EM system itself is at fault, more that its being fed duff information.
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Thanks very much for the feedback, I will have a check of the hoses and throttle body.
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