Not posted for a while, since I’ve had around 25-30k trouble-free miles (apart from self-inflicted odometer jam last Summer, which was an easy fix). Nearing 180k now. BUT... A few weeks ago I had my local garage fit a new cat, an after-market one (recommended). Since then I’ve had both cold start trouble and intermittent shudder / variable revs at idle. Generally, the car needs a foot down start and 1-2 mins warm-up, to avoid a stall when drive is engaged. Start is fine after 2-3 mins drive, but idle is juddery sometimes and, very occasionally, there is a hint of drag in acceleration. Motorway and long-distance driving is fine, though. Since there is an obvious follow-on from the new cat, I wonder if the timing should have been adjusted? Or if the cleaner exhaust has side effects? There is no cold start valve on the M104 E280, because it has VVT. Any suggestions?