rev fluctuations on 4x4 FSi

[bry_obo_dad]

Hi All

First post (and on behalf of my Dad) so please bear with me.

Dad has a 2005 4x4 FSi estate and is encountering the following problems (this is exactly as he wrote them down for me).

1) Engine revs increase by 500 when changing gear during acceleration when accelerator pedal is released.

2) At a constant 50-60mph in 6th gear car appears to accelerate when accelerator pedal is lifted slightly. This gives the impression that engine is firing on 3 cylinders only but 4th operates when less power is required.

3) At constant 70mph the power to engine appears to increase and decrease constantly.

This problem apparently crops up out of the blue and then might disappear for a week or more. I believe the garage have tried replacing coil packs (no luck) and on a recent service they suggested it might be linked to a ?lambda probe? in the exhaust where there was a loose joint they tightened up. 10 days after service the problem came back.

Dad is not surprisingly getting a bit fed up with it now.

Any clues anybody????

Thanks muchly


Bry (obo his Dad)

[phiL&K]

Just a thought, is the drive by wire throttle potentiometer faulty?