I was in a Pep Boys recently and saw an aerosol can of Seafoam with a u-bend attachment and tube designed to fit at the intake seal downstream of the MAF. I read the can, it's designed for combustion chamber cleaning. Something like run engine to operating temp, fit the attachment, start it, run to 2,000 rpm and instill half the can, then shut it off and remove, reattach intake seal, etc. and let sit for some period, the run again later. Seems like it would be worth a try before water experimentation, which can be unpredictable to say the least.