my subaru outback 2004 overheats when going uphill in cold weather, not quite into the red but close, what do i do?

I would have someone look at the themostat and make sure you have them replace it with a genuine Subaru part, there's a difference. Also, have them check your water pump and radiator as well. I understand that Subaru makes a great water pump, but, your car has 200,000 miles. I hope you didn't overheat and blow any head gaskets. See this link below discussing Subaru thermostats and the picture of the genuine and aftermarket units. http://www.smart-service.com/blog/2009/09/prolonging-subaru- head-gaskets

You're getting better, Mark, but it's not the water pump. Yes, check for an OE t-stat, clean the outside of the rad (spray hose and brush), back-flush rear heater hoses with garden hose too in case they're full of scale. You can do this in one operation: remove t-stat and hose; attach garden hose and give that cooling system a good enema. Small chance t-belt cam sprocket is one tooth off. Won't cause CEL but might overheat. But I'm betting on cooling system or head gasket statistically. (Be careful, Mark, what you read.)

TheSubaruGuruBoston- thanks, I'll be careful, I do read lots of articles and while I'm not actually turning a wrench, I'm interested in the mechanics of how these systems work, primarily, because, I try not get talked into unnecessary repairs by unscrupulous mechanics. Fortunately, I already have an honest one, but, who knows, I might be out of town or something. It's always good to have a basic understanding of how your car actually works. And, finally, I like to keep my cars running in near perfect condition.

So, that water pump is so "golden ", it can go over 150,000 miles? I've never heard of anything like that before.

It's the new normal, Mark.

Wow, that's very impressive, I would hope that their CVT transmissions would be better. Years ago, I met a mechanical engineer just prior to my purchase of the Toyota Prius that the CVT technology was way superior and a simpler design to the old automatic transmissions. And, it appears that Subaru migrated all of the automatic transmissions to CVT. So, one would hope that its for the best? We'll see.