A6 C5 AJM 1,9 Tdi - vibration after head gasket replaced

Hi.
After suffering a coolant dump problem for a while I decided to replace the head gasket on my 01' A6 avant C5 ajm code 1.9 Tdi, manual 5 speed box. I left the head into a workshop to be pressure tested and skimmed.
The engineer telephoned me a few days later to explain that he had "broken" two of the injectors whilst removing them but he maintained that 99% of the time they work fine when refitted - as this has happened to him in the past. He also fitted new bushes on one of the injector camshafts.
Somewhat disgruntled I took this on board. I had a mechanic friend fit the timing belt and do the timing for me, he recons that he did it perfectly and I trust him 100% as he has done the same job too many times to mention.
We fired up the car and took it for a run ... and noticed the vibration.
It runs fine at all rev ranges, ticks over perfectly (when stationary and not under load) but when moving and accelerating, the engine vibrates between 1,500 and 2,500 rpm - noticeable in all gears but most noticeable in 3rd gear where the engine is at it's liveliest... to me, it feels as if it's mis-firing. I work with bike engines and know what a misfire feels like.
I have also noticed that it takes considerably more revs than it did to get it moving from a hill start etc and when it does there's a momentary flat spot, it's a different car to drive compared to how it was.
I've had a mechanic friend take it for a test drive and he's mentioned that it could be the dmf or a possible bad driveshaft. He reckons that it CAN'T be down to bad injectors .... but to me it really does feel like a misfire of some kind and the vibration disappears when I take my foot off the accelerator.
Apart from the coolant dump - it was PERFECT before I pulled the head off.
I have checked and re-checked all of the vacuum hoses (as I have elsawin and meticulously photographed and marked all hoses/ pipes on dissassembly) and i've even ran a diagnostic with the basic vag.com software and it showed no errors.
Could it be the "broken" injectors ? I really dispute the fact that it's the running gear as it rolled into the workshop perfectly but has had the vibration only since the top end rebuild. Could the injectors need adjustment ? Can I damage the engine driving it like this ?

Any thoughts or advice would be greatly appreciated.
Thanks

Alan Gunn said:

In what way are the injectors broken i don't understand.

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Me either, i'm going to call him tomorrow. perhaps something to do with the housings ... either way i'll update then ... but could dodgy injector (s) cause this vibration ?

B5NUT said:

The head should have not been skimmed, Audi state that "Reworking diesel cylinder heads is not permissible".
The compression ratio and the squish band will have been changed by skimming so the timing will now be out (compression ignition), so to compensate you would need to fit a thicker HG. Problem is if you don't know how much was skimmed then it's a bit of a lottery to find the right thickness of HG. A lot of people have had to chuck in the head away & fit a unskimmed replacement (worst case)

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Hi and thanks for your input.
The head gasket that was fitted was the one that the engineer that skimmed the head gave me. It was a thicker gasket, matched to the amount by which he skimmed the head, so, the timing should be ok.
Good thinking though, thanks.