Rough idle / idle not stable at all temps

[Dukzzz]

Hi Guys and girls

I have a stock polo gti , and I noticed sitting in traffic that the revs fluctuate too much, as in you can actually feel the cars body vibrate ever so slightly. If you pop the hood you can here the engine not ever changing , if you stand near the tail pop and listen to the exhaust note you can hear its note change.

All symptoms seem to point towards an vacuum leak, has any one else had similar issues? I know it's not the SAI pump as it happens all the time not only on cold start. I"ve checked measured values for lambda readings and they are pulling +13.00% . Which points to too much air .

Anyone have similar or noticed similar conditions ? Or if perhaps next time your sitting in traffic watch you tachometer and see if it fluctuates ever so slightly ? Please check for me . I'm pretty sure it's not normal .

Thanks in advance!

[blackbetty]

hey, i've not had these problems (i did get a bit of a rough idle, but new plugs sorted that out)
could be o2 sensor, could be the thingo that monitors manifold pressure
are you getting a misfire? spark plugs could be sooty, or a coil pack could be shot
hit the search on this forum, see what else you can find on air leaks.