Hello,I am Scott and I will assist you with your vehicle concern.
Your P0300 is a multiple misfire code. The P0310-304 is cylinders 1-4. I would, for starters, check to be sure there is no oil on the plug boots. Sometimes this happens and it causes a misfire. Also moisture will cause this. I f the vehicles engine was pressure cleaned, moisture can get into the plug tubes and create a miss.
The first check, pull the wires out of the hole and check for oil, water in the plug tubes or carbon traces on the plugs.
Finally, the P0496 is a high EVAP purge flow.This could be anything from a stuck EVAPORATIVE canister purge solenoid to a leak in the EVAP system, which can also set the multiple misfires.
The EVAP system can be diagnosed through the use of a Scan tool to interface the system and turn on and off valves while smoke checking it at the same time. This gives a quick and accurate diagnosis.