The main problem this car has suffered since I bought it has been its poor idle. For the first six or so months, it ran absolutely fine, but then it began to stall regularly when idling, and it's steadily got worse. Even now it's got warmer has not improved, and happens equally whether the engine is warm or cold.
The stalling problem did not appear to be a physical issue with the overall running of the engine which remained smooth and even when under power. It appeared to be more to do with the ECU's ability to control the throttle when the pedal is released.
As soon as I take my foot off the throttle, the RPM needle drops rapidly, sometimes stopping at a healthy 800-1000, sometimes stopping really low at around 500 RPM, and at other times not stopping at all and resulting in a stall. It seems like the throttle cannot open and close freely, preventing the motor that operates it (via the ECU) from making fine adjustments accurately.
These cars do have a bit of a reputation for fuel system issues - particularly in the throttle body - which apparently arise due to differences between European fuel and its Japanese counterpart. Jap fuel is more highly refined than European (presumably because of the terrible smog Tokyo used to suffer from) and has far less unwanted extras like sodium in the mix.