My car starts and runs fine but when I change gears and try to accelerate, there always seems to be a delay or a bit of hesitance which makes the car jump. Also, if I dip the clutch (when changing gear) and take my foot off the accelarator, the revs increase slightly and stay there for a few seconds. I've had new oil plugs and air filter fitted. I think it could be some sort of sensor (mass air flow?) but not sure. Also, does anyone know where to get a new, cheap thermostat kit for this particular car as only Vauxhalls sell them at a cost? Any help greatly appreciated.