Have you pulled your codes yet? If not, that would be the first place to start and it should give you a decent idea of where to begin.
Once that's done, if you don't get any errors for the sensors, you'll need to check the basics for all engines; air, fuel, spark. Just as an FYI, it's helpful if you give more details on what you're having problems with. ie: Year, ATX/MTX, and what the symptoms are. Does it crank and not start or does it not crank at all, etc.
Good luck!