3.8 L series II noise question

I have a 1999 Bonneville with the infamous 3.8 L with 147,000 miles (has never been apart), but I think my luck just ran out.... After a 100 mile drive and being parked for two days, I started it this
morning (garage was 40 degerees F inside) and it cranked funny / slow for the first rev or two, when it started it makes a ticking sound (collapsed lifter??) Kind of loud, and the exhaust has a definite poof, poof, poof (dead cylinder sound). I know about the coolant leaking upper intake manifold into the crank case thing, but the oil looks good. But low and behold I see coolant around the outside at the throttle body end of the manifold and on the block..... leaking at the throttle body / manifold junction I suspect.
My questions: 1) how likely is it that the funny sound / slow crank was that coolant had leaked into the intake and into a cylinder(probably somewhat likley), and 2) what damage could I expect to find (bent connecting rod?? If it was coolant in a cylinder, I am hoping it forced an exhaust valve closed causing a bent push rod or the lifter to collapse).
My plan of attack is to pull the valve covers and check for a loose push rod as a starting point..... then remove the throttle body and check for signs of coolant on the inside of the manifold... hoping for a collapsed lifter or bent push rod and no "major" damage (bent connecting rod, piston damaged, bent valve stem etc.).
Anyone with past experience and would like to share, it would be greatly appreciated. Thank you ......
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On Tue, 03 Jan 2012 20:18:02 -0800, snipped-for-privacy@rlfarms.com wrote:

My son and I did his before it failed. Used a Dorrman plenum and the updated GM metal frame LIM gasket. Go here: http://www.bonnevilleforum.com
Register so you can search. That forum has all the answers on Bonnevilles if you browse/search. Plenty of threads on failed plenums/LIM gaskets.
--Vic
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We went through this with a 1998 Buick LeSabre. It went from no problem to cylinder full of coolant within minutes when it failed. We never had detectable coolant in the oil. When it was pulled down, it was the deteriorated plastic plenum. No damage was found to any valves, pushrods, connecting rods, etc.
The Dorman unit was installed and we had no further problem.
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