Q: While driving car bucked then dropped speed, shut it off and now it won't start again.

Hi There, As you may know the oxygen sensors which are part of your emissions system read exhaust gases to determine whether or not the appropriate amount of oxygen is present in the exhaust. Based upon this reading, this information is relayed to the car’s ECU which then makes a determination as to whether or not to add more or less fuel to the engine. When too much or too little oxygen is present, this will cause check engine light to come on. Too much oxygen may be present in the exhaust gas due to things like an exhaust leak, a vacuum leak, a faulty mass air flow sensor (causing a lean fuel condition) or faulty fuel injectors. Too little oxygen may be present in the exhaust gas may be caused by things like a clogged air filter, a failing mass air flow sensor (causing too much fuel to be introduced to the motor), bad fuel injectors or a clogged catalytic converter. When the O2 sensor is not working properly, this will cause false readings to be relayed to the computer causing inaccurate adjustments to be made to the intake and fuel system in your engine. Any of the above problems may cause the car to jerk and possibly even shut down depending on the severity. When the engine shuts down, this will also cause the oil light to come on as the oil pressure will have dropped as a result of the engine no longer running. I would suggest having an expert from Your Mechanic come to your location to diagnose and inspect your vehicle.