TCC code--what to do?

I bought the van used and it had already had it's tranny replaced once (at 150,000). I have a TCC code and from the sounds of some of the questions in you site, I need to check everything out before I just let someone change the trans out again. The van runs fine when not at operating temp but once it gets there the trans lurches like going into passing gear, begins a high pitch whine, rpms are up (I don't have a tach) and it won't shift out of second. Nothing stops it except parking and allowing it to cool. What else should I look at before condeming the trans.