Don't get rid of your shroud, I think you'll only be going backwards. I would at least try changing your t'stat first. There not too expensive. Then go from there.

Also you may want to try instead of regular Antifreeze that stuff that comes in the can. I forgot the name, but I think the fluid is actually pink. I've used it but had a brain fart and can't remember what it's called. Anyone know what I'm talking about?