Did have a problem like that one one of my trucks. Found it was rain water leaking both thru the hood seam down onto valve cover and endering thru valve cover air vents AND water going thru air scoop drain hose down onto valve cover and entering also thru valve cover vents. May help. I redirected the air scoop drain hose and leave a 2X4 on the valve cover to deflect rain water until ready to drive it.
