Engine problem
2001 Audi A6 6 cyl Four Wheel Drive Automatic 122000 miles
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I have a 2001 2.4 A6 Avant Quattro, the engine runs smoothly after a cold start for a few minutes, then as it warms the idle occassionally dips , two or three times a minute. It is not a misfire and I have checked the condition of plugs and vacuum system (replacing a split pipe) but the problem remains. Also on a hot restart the engine revs rise to approx 1200 rpm then dip to 200, then bounce back up to 1000, bounce back to 500 then eventually settle at 800 with the occasional hiccup as described above. A computer diagnostic has revealed no fault and the dealer says he thinks there is nothing wrong, but it never used to do this - help ?