[knelleken]

if you have a programmer or chip. that is probably your problem. it alters those signals in order to increase performance and increase air(turbo output) and fuel mixture and fuel timing. if that is in fact the case, you might have already overworked your turbo and it might be on its way out.
you can get the ckp sensor recall done for free at any dealer. it only takes 3thents to perform. get it done man.