Hi I'm having a problem with my Ford fiesta st2 2014 at first when I parked up and and the car was idling the rpms started going up and down and the car just shut down ... re started no problem was fine a week later while I was driving it started loosing all power then started juttering and shut down then wouldnt start back up .. but if u left it for a little bit it would start back up but go into limp mode ... but run fine till the engine got hot then shut down again ... if had it plugged in and its saying about fuel presure in fuel presure regulator . And fuel pressure regulator performance... iv changed the fuel pump in the tank iv changed the fuel pump relay moduel and still the same so was wondering if it could be the high fuel pressure pump .. please help?