Thanks. I'm thinking the same thing without really trying a voltmeter. I also get a rapid succession of clicking when trying to start which is typical of a battery failure.

 

If the starter is turning over the engineslower than usual, it could be a low battery. Is your clock resetting itself every time you start? The fact that it only does this when warm suggests something else. I had the same problem a couple of years ago - replaced the IAC, MAF and finally the TPS. It was the latter in my case.

 

Did you ever figure out where the coolant went?,no one responded to that yet.