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Sea Foam Engine Treatment (16 oz.) - MILSF16
AquaTune.com - AquaTune Water Injection Systems

I would take a look at both of these links.
The second one will illistrate why water through the vacuum line is not a problem and the first one is

intake of water is basically what is done in this hydro injection system-they have been around for years without problems.
It might be something to look into to solve your low end torque and hp problems
also you will never have to clean the engine again lol

As far as the ATF-i wouldn't recommend using that because it could potentially clog up your sensors because it is very viscous- however, it is not a bad suggestion to use in a pinch but seafoam is a better way to go.
The first link will show you how to use seafoam if you have never used it before. it is a good product and every engine -especially high mileage ones could use a bit of cleaning every now and then.


Good luck guys