1997 DOHC neon HARDCORE over-heating!!!

My neon sport is overheating like crazy. it was pressureizing the coolant and spewing it out so i did the headgasket. three days later it started again. now i've changed the thremostat the coolant temp sensor made sure the fans are working and gone through about eight liters of coolant in about two weeks. im out of ideas!!! can any one help!!??