[quote=scottsdale1955;6957355] UIM. I highly doubt it was replaced, as I'm the second owner, and it had 44k on it when I bought it two years ago.
QUOTE]
Check for the circles on the upper intake, one of them giving the year of manufacturer. If there are no circles or the date is later than 96 or 97, it has been replaced.
http://i86.photobucket.com/albums/k1...earstamp-1.jpg
If you are leaking coolant into the upper intake, that gets aspirated with the incoming air. The plugs would be nice and white from the steam blasting as the coolant burns off in the cylinder. Have you had any stumbling from the engine or any missing when first starting it, e.g.?
If it's a lower intake gasket between it and the heads, the coolant may seep into the cylinder while the engine is off and hydrolock it.
To me, your starting problem lies elsewhere. But I'd put the UIM/lower gasket work onto my bucket list, along with replacing the fuel pump and sender, since the tank must be lowered to do that. Been there with the leaking metal tube from the sender to the fuel filter. Rusted even though I sprayed off the car underneath 3-4 times a winter.
If it is the original UIM, I'd personally recommend the APN upper with metal sleeve, ineedparts.com. For lower gaskets, use GM metal protected gaskets for the lower intake to head gaskets.