The O2 sensor won't come into play when starting the car. You need to determine if you are loosing spark or fuel first. The crankshaft position sensor is used by the computer to calculate when to send spark and fuel to the engine so if you loose the crank signal it is likely you will loose spark and fuel. But if you have spark and don't have fuel then you would start trouble shooting the fuel side of the equation. Best to put a fuel pressure gauge on the engine to determine fuel pressure reaches spec on cranking. It could be so many things, if the fuel pressure regulator leaks it will loose pressure, if the temperature sensor is sending a false temp reading to the computer the computer may thing it is below freezing and flood out the engine (like too much choke on carburetored cars years ago). Replacing parts without testing them and proving they are wrong is rarely cost effective. Autozone have some popular workshop manuals for free on line once you register (for free) on their website http://bit.ly/autozone_repair_info. There is also a company that independent auto repair shops buy their information from that the same information inexpensively to do it yourselfers. The information is year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online