Chris, Sounds a lot like you have air in the cooling system. If this is the case, you may just need to "burp" the radiator. If symptoms return, one or both of your heads might have exhaust gases escaping into the coolant. I had this problem and remedied it by a simple re-torque of the heads, but this is not always the solution. In some cases a head gasket replacement is required, or with cracked heads, a head replacement. 

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