I was in the process of bleeding and cleaning my cooling system using water. Well I have added probably 4 or 5 waterboytles full of water to my empty radiotor. I turn my car on to mix the water around and get ready to drain it when necessiary. I would rev the car up to about 4 or 5 rpm and water (as my coolant) was gushing out the back of the motor under intake manifold passenger size. I had just changed my IM gasket so maybe its sleeping out between head and IM? Or maybe a hose I can't spot is leaking. BTW I idle at 2 rpm and it will drop down to 1 then back to 2. Then after awhile it will go to 1.

 

There's 2 lines back there you could have left disconnected or broke upon removing.

 

you probably missed connecting one of the hoses, x2 check that they're all in place