Throttle body heavy click

when i turn the key in my 1996 xk8 i get a quite a loud click.coming from the throttle body.i changed it about a year ago.the car is still having work on so not been on the road yet.i was starting it from time to time,as you i thought,nice day put the old one back on to see what happens.exactly the same click.anyone got a solution??? please.