Plugs look really clean. Intake is leaking. Had the same problem last year. At idle it wouldn`t leak, but when rpm`s start to come up it would suck water and foul plugs on all 4 corners. I was running a splash shield.This keeps hot oil from hitting your intake and heating it up thereby heating your mixture and not enabling your motor to get a cool dense charge to make more bang. I didn`t like the way it seated to begin with so I had a heads up. Removed splash pan I only use fel-pro gaskets and high temp RTV. DO NOT use the 2 end gaskets even if they are neoprene `cause they are just gonna move on you. Take a metal can and block off the heat risers in the heads. Just trim a little square out of can and RTV over heat riser. This is FREE Horse POWER and will save you fuel. Only downfall to this is you cant heat up your lunch on your intake anymore.