Have you tried burping the coolant system yet? I ran into some cooling issues with my 03 and it was all because I didn't burp the system right.
I haven't touched it since I let it idle to see what it did the one day. After that, I gave up for the time being and parked it. The thing is it ran great before that so something caused it to hiccup the one night. I can't see how it randomly ingested air into the system. I ordered a stainless crossover plug today and maybe once that's here I'll throw my Reische in and see what happens.