e39 Acc stutter but no power loss!?

[cliffdunedin 8]

I noticed a few days ago that there was a stutter/vibration that had developed as I accelerated from stop or under low RPM to a higher RPM, it seemed to leave at higher speeds and as the engine heated up. I went home and i saw the fan slightly wobbly so rolled up a newspaper and bingo the fan clutch was gone, I ended up buying a new clutch and installing it, the wobble of the fan is gone but that stutter/vibration is still there. I don't seem to lose any power with these vibrations but am stumped what it could be because of this no power loss.

Does anyone have any suggestions?

nb: Waterpump and belt has been replaced in the last year.

TIA guys

[B.M.W Ltd 950]

Scan it... I need to say no more

[cliffdunedin 8]

Scan it... I need to say no more

Sorry forgot to mention, no codes.

[B.M.W Ltd 950]

Sorry forgot to mention, no codes.

Then the brain needs to kick in with hands, ears and a nose under the bonnet unfortunately with a few other test tools and maybe a real or better scan tool. I'm thinking unmetered air flow as preliminary causing lean mixtures

[cliffdunedin 8]

Bit of a late update but it was a cracked CCV pipe!

Noticed the small amount of oil leaking by chance when checking that the camshaft sensor was fine.

[polley 916]

Bit of a late update but it was a cracked CCV pipe!

Noticed the small amount of oil leaking by chance when checking that the camshaft sensor was fine.

As Glenn mentioned, unmetered air flow.