Showing code PO300 multiple ;engine misfire detected; What repair items ?

Hello, Multiple misfires can be caused by a laundry list of items, but finding the exact cause is why technicians train for years to put the ASE badge on their uniforms. Spark plugs can be a cause, but they don't tend to fail together. Fuel filter is better thinking, but if that did not fix it, you might want to seek professional help. Reason being is a diagnostic fee is likely not much more expensive than you will pay for the next part you try. This becomes more important as you run out of things to try replacing, since diagnosis will flush out the cause on the first try most times. When considering a multiple cylinder misfire, it is most likely that something effecting the entire engine, or the cylinders that the misfire is centered on, is causing the issue. For this reason, it is important to understand which cylinders are misfiring and why. This could be a bad intake manifold intake manifold gasket, bad fuel injectors, bad fuel injector seals, a head gasket leaking at those cylinders, or a host of other issues. Diagnostics is the way to go, and I would probably start by checking the fuel system for fuel pressure.

For does people the have problems with the Gmc 4.2.L6 or v8..with mis fire cylinder. Rather is 4 or any other cylinder.i am sure the many of u want the right answer..well I was work today in my friend 2005 GMC envoy 4.2.L6 and I use my scaner.and I got code for misfire random cylinders. .well I change the spark plugs and one coil number 4..and still has the problem..so...the injector was fine..and has new spark plug s and one new coil..but at the end.i check the coil boots with the spring. I found out .the 2 of the spring inside of the boots.was broken..that was the reason of the multiple mis fire.so I when to auto zone and buy a new package of new boots and springs for $21.99..I when and replace all 6 and now is working perfect..so make sure always to check grounds..that spring is ur ground in ur boot coil..a looks good.but u never cant see the center.where the damage is..I hope I answer ur problem.