P0300 Chevrolet - 4.3 right bank is lean left bank is rich

Question

replaced plug wires cap and rotor 144,000k. starts fine but misses and down or power

Answer 1

P0300 Random misfire

Check the oil, see if it has the smell of raw fuel, what can cause one side of the bank to go rich  and one side of the lean are the fuel injector lines and even the fuel pressure regulator