I have been having a P0300 random misfire since I bought the car used and I just noticed the schrader valve cap that relieves the fuel pressure is missing. Could this be the cause of my P0300 random misfire? Where do you think I can purchase this cap? Thanks for any help.

 

dont think the cap has anything to do with the pressure..just there to prevent debris/particles to go in sprocket

 

it won't cause your mis, it is just bto keep the valve clean