sheesh I dont know about using a garden hose (hydrolock??) but I used to do this on my 79 Camaro by using a windex bottle with water in it. I would spray down my Holley, and while I don't recall loads of crap flying out the exhaust, I do know it did help things out.
What you CAN do on your car now is...go to the ford dealer, they sell this decarboning cleaner, and you can spray that into your intake while the motor is running. It more or less does the same thing but it is a foaming cleaner...there is a bit of a proc to it. I will do this every 5K once I clean out my intake manifold/butterflies in the next few weeks.
