Lean, it used be 14.5 or so on steady off boost throttle, now it's high 15s, I'm too afraid to put more than .1 or .2 of a bar pressure through it, it's just doesn't seem right. Coming up to traffic lights or a junction I need to give it throttle to stop stalling.

Nothing has changed in the last few weeks. I had the intercooler off to change the rad a few weeks ago, but the problem didn't happen straight after this, it was maybe 100 miles later. I don't use the car everyday, but I do need it every now and again