renault laguna sports V reg?

i have had these parts fitted to my car... coolant,crankshaft, manifold pressure,throttle position sensors also coil pks 4, spark plugs 4, fuel pump and fuel filter plus fuel pump relay to my car to stop the juddering without any luck also it now and again comes to a halt as though some one has switched the engine off but after a few seconds it starts up fine and drives off. please has any one got any more ideas as this is costing me an arm and a leg thank you