Welcome to the club, Paul. PO251 is Injection pump metering control according to my list of codes- 2.0 and 2.2 litre duratec engines. It could have been not enough fuel getting through when you gave it a bit of welly. What mileage has your car done? I ask that question as glow plugs are expensive things to buy and they need careful looking after. A month ago I had my 2.7 diesel Terracleaned and it has made the world of a difference. It has made the car a little more responsive and given me a better MPG. Other diesel owners have had the same experience with this service. It might be good for your car at a cost of less than £100. Regards, Peter.