Some of you may have seen my recent thread about a new head gasket and head skim on my 1.9 130. Since the work was completed the car is noticeably down on power. The car struggles to start cold which it didn't before. Throttle response is erratic at times, power comes in surges. The car struggles at all revs. There is not a noticeable point that the turbo comes in, it's almost as though it doesn't work.
What are peoples thoughts on causes? Of course the garage say that nothing they have done has caused it but it went in driving sweet as a nut and came out like an asthmatic n/a old diesel.