Bad Headgasket or not?

My van is overheating when it is idling.It will blow coolant out the overflow.I noticed coolant laying on the top of the transmision.I can also smell it burning.The van is running fine though. I replaced the rad cap and even took the thermostat out completelly. It has been a couple of days now. I am still loosing coolant I have to add everyday. It will only overheat when it is sitting still.It is driving me nuts. I am a pretty good auto mechanic but I cant figure this one out? What could it be? I am hopeing it is not a headgasket.

What model year is your van?
Look where the aluminum block is connected to the iron main block and see if there are streaks from the antifreeze fluid leaking out.

It is a 98 voyager, 3.0 I tried to see were the coolant is comming from but the only place I can see it is on top of the transmision. It doesnt seem to be leaking any more but I have to keep adding coolant.

If it only happens at idle, make sure your cooling fans are working.
If they are not, the van will overheat when sitting still (for a period of time)
and be ok when moving.

I don't have any experiance with the 3.0, just the 3.3.
I heard 3,s have head gasket problems and terrible water pumps.

i have a 3.3l that was doing the same thing and at first i thought it was the water pump so i replaced it which didnt do anything but what was causing the problem all along was a peice of 5/8 heater hose about 5-6 in long i think it was some sort of thermostat bypass but i pulled it out and it was all craked open and stuff i have also blown a head gasket but it didnt run normal when that happened so your problem may be as simple as mine was just check all the hoses to see