2000 Chevrolet Silverado 5.3L with engine code P0300

Question

I have a 2000 Silverado 5.3. Has a code P0300 starts fine when cold but when it's hot it starts and idoles very rough for 5 seconds then smoothes out but still has a shake. Only acts up at idol.

Answer 1

P0300 Random misfire

Random misfire mean more than one cylinder has misfire condition. If you have a scantool that  can read cylinder contribution this make it much easier, Other than that you need to do just the basic inspection, some of the cause for P0300 can be from worn sparkplug wires, igntion coil , fuel pressure regulator.

 

The fuel pressure regulator if its vacuum valve ruptures it will seep fuel into the intake manifold and does cause a P0300

 

Worn sparkplug can and do cause random misfire

Ignition wire and its coil. sparkplug wire that are worn can and do cause a similiar condition to what you are experiencing.

Answer 2

P0300 CHEVROLET - Cylinder Misfire Detected Random Cylinders
Read more: https://www.autocodes.com/p0300_chevrolet.html