86.5 7MGE Problems

[86.5 7MGE]

OK, so I'm starting to think that I have a BHG. My symptoms include...radiator fluid spraying out constantly from the purge port on the reserve and when I drive sometimes not all the time it will start hesitating while the accelarator is pressed. It seems that I have to fill up the radiator every two days or so because of all of the fluid being purged out. I had Pepboys do a pressure check on my coolant system and they said it was my radiator cap at fault. So, I replaced all of my coolant hoses and vaccum lines to include the radiator cap and thermostat...is there something else that I can try that I'm missing before I assume that it's a BHG??? I still seem to have great power and only powerloss when my radiator gets low on coolant or it starts to hesitate.

At the same time I see traces of black smoke on my rear bumper and I know that white steam/smoke is a sign of a BHG due to coolant mixing in the combustion chambers. Could this be also from worn out piston rings?