What you need to do is pull every thing apart. I have seen before where a tech will not get the crank sprocket all the way tight and the trigger wheels moves around. I have also seen where they pry on the crank sprocket to get it off and end up bending the trigger wheel. They also could have cracked the crank sensor for over tightening. If for some reason the tech pulled the whole sensor off if he did not get it routed the way the wires go then the tbelt will rub on it.


DTC P0300
Random misfire detected. Possible causes are: connector or
harness, faulty ignition coil, ignition power transistor, spark plug,
ignition circuit, injector, HO2S, compression pressure, timing belt,
air intake system, fuel pressure, or CKP sensor.

The ecu also must see these conditions to check for a misfire
300+ seconds of steady state RPM less than 80% throttle position
À Engine coolant temperature -10C or higher
À Intake air temperature -10C or higher
À Barometric pressure greater than 76 kPa



So they have the pan off and showed you the bearings confirming the bearing are shot?