[PatrickinWA]

1997 Bravada 4.3 ~ Dexcool-3 Me-0
My coolant looked like mud when I first got the truck a year ago. Flushed her out 3 times myself before I took it to the mechanic who charged me $90.00 and told me I needed a new radiator and water pump, $692.98 was the quote. I replaced radiator, pump, upper/lower hose, heater core hoses, and thermostat. Only took about three hours and total cost was under $200.00. Truck ran great for about two months. Since it has gotten cold here in WA, I have a new problems. Here is my list of symptoms:
1) Coolant Loss - About a gallon per week, nothing under the truck.
2) A slight mist of coolant,(like you would see if you had a pin hole in a hose) appears from under the hood when I turn off vehicle. Pop the hood and there is nothing, just looks like the windshield above the heater core is steaming.
3) Slight smell of exhaust in the cab
4) slight smell of antifreeze in the cab
5) Small decline in fuel economy
6) Very slight but noticable erradic idle at a stop light, doesnt happen if the truck is in neutral or park.
I am thinking the steam could be coming from the heater core, but I am not getting any other symptoms of it going bad. Carpet is dry, windows arent fogging up, getting great heat. I am wondering if I have gasket issues? If so, which one/ones could they be? There is no coolant or water apparent in my oil, (changed oil 2 days ago and let the old stuff sit in the pan for a while so I could check).