If you drove it that long, that is all the hotter it is going to get (yours anyway)- one thing to remember is don't OVERFILL an alli, they don't like that!!!! :(
If you find out, let me know- I have a buddy that has one that is doing the same thing. The only thing that I can think of is the module, but not sure if the heated seats run through that????
yeah, you need to mix it 50/50- not good to run it straight. also, IIRC the two thermostats are different temps from each other. what "heater core" trick did you try (never heard of any tricks for it??)?