P0300 Chevrolet -possible fuel pump and water in tank ?

Question

Change fuel filter brown pressure dropped on pressure test to 20 after turn off also flashes if not fully warmed up the car for min 10 minutes plugged in

Answer 1

P0300 Random misfire

Loss of a specific fuel pressure will definitely cause a random misfire condition , but it should set a lean code condition  this would be more specific, If there was water in the fuel tank then that would be a definite P0300.