Engine help

[Bhadn]

Hello I've just purchased a A3 3.2 Quattro. I'm just after some advice. The issue I'm having with it is, on start up, when its running on choke and running rich, it idles fine, the revs come down to around 700 and it sits fine. I do feel a small a flutter from the engine which does feel like an engine mount. 

Once it's at running temperature, the revs start to spike and bounce between 1k-1.5k.There is an exhaust leak on the flexis and they are between o2 sensor 1 and 2 but its not bringing any codes.  
I cleared all the codes and took it for a drive and it came back with these codes: 

Idle Control System RPM Higher than Expected. : P0507 sporadic 001 -Upper Limit

Bank 1: Camshaft B (Exhaust); (Over-Advanced) : P0014 sporadic 008-Implausible Signal

Bank 1: Camshaft A (Intake) !Removed! Setpoint not Reached (Over-Advanced) : P0011 sporadic 008-Implausible Signal

The has had a new chain fitted back in 2017. Am i right in thinking either the chain has stretched or both variators on the cams are playing up.