I have my head gaskets replaced in November and a few weeks later the check engine light came on. Took it to dealership said that #6 cyclinder misfired and they could not find a problem. Said it was ok to drive. CEL would countinue to go on and off periodically. This week engine engine overheated and antifreeze smell and white smoke was coming out of exhaust. Took to dealership, said that they are waiting for an answer to either replace head gaskets again or replace engine. Please help. What do you think needs to be done?