Sweet Cream

Hi Fordies, still trying to overcome the hiccups in my XF EFI engine in my XC. Starts immediately hot or cold and runs beautifully until I step on the gas from a standstill in first gear. Engine responds immediately then jerks until I ease off the pedal. Slip it into second gear and run through the other gears and it runs smoothly anywhere . Stop and take off and under load in first it coughs and jerks until I ease and get going and all ok. Usually smooth as silk. Thanks for your suggestions and tomorrow, Sunday, I'm checking and cleaning out all fuel and air intale lines, replacing fuel filters, plugs and leads and checking the regulator on the fuel rail. After that I haven't a clue. Any more suggestions would be amazing. 

Cheers SC