[86.5 7MGE]

I would check the oil just in case to see if it has any milky color to it...the 7M motors have a bad rep for BHG do to poor torquing by the manufactor... And the motor is great it will still run like a champ even though it does have a BHG...If not, then it could be a rich mixture causing the problem...also you can check your plugs to see if they are brown in color this will also let you know if you have a BHG, they should all look similar white and not brown if you do pull any with brown on it then that cylinder has been envaded by coolant due to a BHG...if I'm wrong I'm sure someone will correct me.