Hi. I've looked through various threads on this but have not found anything that relates to my specific problem. Up until yesterday my car (1.8T) was running fantastically. Then the yellow ECS light starting flashing. Under acceleration the engines bogs down and starts to splutter. If I am gentle with the accelerator the car reaches 80mph very smoothly, but if I push on the throttle a little harder it bogs down again. The owners manual says that this warning light refers to a catalytic converter issue. I have had a REVO stage one remap and up until yesterday I was very pleased with how the car was running. I run on only 97RON fuel and the remap was done taking this into account (I haven't used a lower RON fuel since the remap). The car will also bog down when accelerating off a roundabout or from a junction...but again, if I am very gently with the throttle it picks up smoothly, if not, slowly...which is great except that the car behind me starts to catch up very quickly. I hope to get the car looked at tomorrow, but was wondering if anyone had any ideas as to what my problem could be? Thank you for your replies in advance.