P0300 Chevrolet -

Question

truck run fine at 9:oo am next time i started it at 4:00 multiple misfire/random at idle and lack of power when driving been running fine egr  code p0401 has been on for a year

Answer 1

P0401 Exhaust gas recirculation insufficient flow detected

Couple of places has to be checked for this condition one would be the condition of the sparkplug wire , and the ignition coil for any arcing   and its sparkplug wire  to the distributor cap, if that area is fine turn you attention to the fuel pressure regulator, because this is intermittent, , if the fuel pressure regulator leaks fuel into its vacuum port it can cause a intermittent misfire. and it can leak internally when it wants to.

​ Check the vacuum hose connection here for any fuel seepage if any is found replace fuel pressure regulator

​ Check the sparkplug ignition coil for any signs of arcing or secondary seeking ground

​ spark plugs wire that may have exhaust damage causing secondary ignition seeking ground