wide open throttle 1

My 1985 YZ250 goes to wide open?? might be the carb. Put a new carb on got it running for i few minutes changed throttle cable and twist grip then all hell broke lose it went to wide open kill switch no help turned gas off no help pulled spark plug wire off no help pulled gas line off carb no gas there. How is this possible been at wide open for about 3 minutes water in radiator boiling over another minute it finally shut off. Is this thing posseseed? Any help out there.