Y'all might want to check this thread with a similar title currently nesting one thread below yours (prior to this bump):
http://www.automotiveforums.com/vbul...d.php?t=487454
You can also do a search on google for 3.1 head gasket and be amazed by how many people have this problem (and/or the leaking intake manifold gaket). My son's Monte blew a head gasket at 70,000 miles two weeks after we had the transmission rebuilt for $1900. I pulled another engine from a lumina in the junkyard and put it in and it had a blown headgasket too! Must have been a monday morning/friday afternoon car...
Short answer: you have classic signs of blown head gasket. A competent mechanic can diagnose it by testing the coolant. Since you seem to be mixing coolant and oil, the oil is losing it's lubrication and things that are supposed to be protected by the oil are wearing out at an accelerated rate. If so, in the not too distant future, your engine will become damaged beyond reasonable repair likely throwing a rod. Don't leave it too long to be checked.
I'm not sure who did your previous head gasket. If professionally, you might want to go back and ask them whazzup? Did they follow the proper torqueing procedures? Did they check the heads for warpage etc? Since this is a V-6, you have two heads and two head gaskets;perhaps the other one is now blown.
Toyota owners with the 3.0 straight six have a "Club BHG", sounds like we need to start one as well.