Hi all, having a problem starting my b4 once every week or so. Car will start normally most of the time but once every so often will keep turning over nd fail to start.if i leave car for 20mins might start otherwise if i put jump leads on it will start (even though engine wont be turning any quicker). I have new starter and battery put in car in last month. Car always drives perfectly so just issue in starting process. What would ye recommend to check/change next in my process of elimination? Plugs,sensors,ignition coil?? Any help greatly appreciated