Engine Part Replacement

[oldskool]

Dear Sifus and Gurus out there,I would like to know if you guys have ever change a pulse generator/sensor for your M40B18 engine. If I am not mistaken its also called crankshaft sensor.Apart from that, did any of you change you ignition coil and distributor cap before as I am sure it has a life. How much will an AFM cost? Mine has a deep groove in it and the idling runs when it get stuck in it. This will cause the rpm to drop or surge up to about 1200 rpm when the aircon kicks in or out. Please advise.Thank youOldKooL