bmw 520i 91 idle problems

can any help got a bmw with idle problems when warm goes up and down then cuts out have changed the idle air valve and still doing it also had a bloke out and he says it the alternater could this b right or not thanks
shaun
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More likely a vacuum leak, throttle position switch or in the event of oscillating idle the O2 sensor.
Unlikely to be alternator.
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thanks 4 that any ideas where 2 start on it
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Does it have an M20 engine or an M50?

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Look for oil leaks coming from the engine and if you find any just trace it back. If none, check all the air and vacuum hoses and feel around underneath too. Also check things like the O rings on the dipstick and anywhere else where air might be getting into the engine.
Steve

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hi thanks 4 that checked all the hoses and no oil leak any where any other help
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