Although the "common" failure of the intake gasket causes coolant to get into the oil, it IS possible for an intake problem to dump coolant into a cyl. More likely a head gasket or head - but I would not rule out the intake out of hand.
Yes, I'll agree it's possible for intake plenum to crack and deliver coolant into the cylinders, but I've never seen this and is so large a longshot that there are much better avenues for investigation.
Clarification: I've never seen the plenum crack on this engine. I've seen it numerous times on the 3800. This enging has an aluminum plenum. The newer 3800 has plastic.
No, it's not "possible" for an intake gasket problem on the 60 degree v-6's to dump coolant into a cylinder. The intake passages are nowhere near to the cylinder runners. If you actually look at these engines while they are apart (which I happen to do on a daily basis), you will see why this can't happen.
Ian
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