Hi all, Peugeot 308 1,6hdi 90, 59 plate. When touching accelerator pedal to reach 1,000 rpm it fluctuates between 1,000 to 1,200 revs. It does it in neutral which is not really a problem, but when doing 30 mph in 4th gear or 35 mph in 5th the car starts jerking forwards. It stops if I accelerate but is a pain in the ass when chugging along in 30 mph areas. Any help please.