David Wallace

First of all hello to everybody. I'm a newbie who lives in the Kingdom of Fife. I have owned 6 Jaguars in the past and I'm now on #7. It's a 2010 XF 3 litre. and I have a problem. When ever I use kickdown she changes gear as expected but when I take the foot of the Restricted Performance comes and the car runs out Of puff. Stop and switch the engine off leave it a couple of minutes and evrything goes back to normal. Sometimes when sitting with engine running it starts to run rough between 750 & 1000 RPM. Switch off and restart and 9 times out of ten She will reve as smoothly as she should. I've had on a diagnostic at a diesel specialist and it does not show that anything is wrong. Anybody with ideas or suffered a similar problem.