Hello Everybody! I currently Have a p 0301 code that has been constantly coming up. I have replaced multiple items on my 2001 chevy blazer 4.3L vortex engine and it still comes up.

Items replaced so far: Crankshaft position sensor, Spark plugs, Spark plug wires, Ignition coil, 4wd switch, Map sensor, Fuel injectors, Camshaft position sener with new Distributor.

vacuum lines are all good and the cylinder pressures are all within good running range from 125-130psi.

Next I was thinking to change the fuel filter but other than that I'm stumped what could cause the code besides maybe bad wiring somewhere. Any suggestions would be appreciated.
Thank you for reading and taking the time to answer