I have noticed coolant loss and my 5.4 is running rough / missing, I have noticed that with the cap off the coolant reservoir the water level will drop 2 or 3 inches when I throttle it up. Then when I release the throttle the water bubbles back up to a normal level, also I have what appears to be water dripping out of the tailpipes. Could this be a head gasket or can this be something else