Needs the fuelling setup correctly for starters.
Also you need to know what chip it is to set it up correctly.
Was the chip Specced to his T34/0.55 turbo or a standard T3
These things all matter, personally there is NO WAY i'd be putting a "random stage3" chip in my car i knew nothing about, especially without checking the fuelling and making sure it's right for the spec of the car. Your problems are porbably minor, but why even bother risking it? £100 is less than the cost of an engine rebuild.