97 Ram 1500 5.9. over heats when radiator cap is tight. If on loosely doesn't. on 1997 Dodge Ram 1500

97 Ram 1500 5.9 overheats and boils over very quickly. If I leave the radiator cap on loosely doesn't seem to overheat. With cap off, raising rpm's level in radiator drops down for couple of seconds, then over flows. Have replaced fan clutch, thermostat, and cleaned radiator. Have water/oil foam on inside of oil cap but no foam on oil dipstick. No foam in radiator but am putting so much water in it might not see any.

Asked by for the 1997 Dodge Ram 1500
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Are you putting water in it , or the proper mix of coolant? .....After sitting overnight, have radiator full and cap on tight, start it and hold the upper rad hose in a safe place and feel for air bubbles and a rapid increase in pressure in the hose. If you 'feel' bubbling or the hose can't be easily squeezed (like just before starting) then you've probably got head gasket problems(in my opinion).
I greatly appreciate your response. I am putting water in it at this juncture, simply because I would have to
put 2 or more gallons a day of coolant. I simply can't afford it. But other than right now, I have always
run the right mixture of coolant and water. In fact I use distilled water, in a effort to reduce minerals that
can aid in the formation of rust. Would you be Kind enough to educate me a little further? I was
thinking head gasket, but I'm not sure about the difference between gasket and head symptoms, or
block for that matter. Could a cracked head produce the same effect on the upper hose? What symptoms
would be different?

Thank you kindly,