Sounds like you blew a head gasket. Check the radiator, pop the cap and look for girgling bubbling etc along with the oil in the pan. Water could be in the oil.
I'll check out the radiator. Oil looks clean from the dipstick...
I would think a blown head gasket would really dampen the low down power and it seems like the liquid would resemble antifreeze a little closer; but I've no experience with blown head gaskets. Thanks for the input!