I've been struggling to find a solution to the P0300 "Random Misfire" code for awhile now. I've changed the plugs, coils, UIM gasket, and PCV valve/tubing to no avail.

Has anyone came across this code? If so what did the problem end up being?

 

Vacuum leak is the most likely cause of this issue.

Followed by MAFS and Coils.

First test is a Vacuum leak check.

Second is check for exhaust leaks.

3rd is monitor Fuel delta (Fuel trims)

 

i've had a random misfiring code. i also swapped out a coils, plugs, gasket and maf and the misfire still came back and engine misfiring too. only one code registered and never pointed to any individual cylinder, turned out to be a bad engine computer due to the previous coil burning and shorting out the ecu. I swapped out the ecu and problem went away.