I've had amisfire for a while now, fitted a coilpack conversion at the weekend and it ran fine afterfitting, used the car a gain this morning and it misfired like mad until I put my foot down and it threw out a lot of grey/white smoke, ran fine after that. Had the same problem when I went out to lunch, wehn I went to come home from work it would start first time.

Could this be a fuel related problem been using Tesco 99 Super Unleaded since September and I've had the misifre for ages but it got worse recently. I had 3qtrs of a tank of Tesco stuff left which I've now topped up with Shell V-Power.