On my way to the dyno today, which is an hour from my house, my car started poping out of second gear. My 3rd gear syncros is pretty worn and grinds when I shift from 2nd-3rd at high rpm, but my second gear has never had that problem before. The problem went away on my way home from the dyno, where the car poped out of second a couple times, but sure enough as soon as I got home, it started acting up again. It seems as if this only happens after Ive been driving hard for a little while. Does anybody know what the problem could be, and could I get some suggestions as to what to do? I might change the tranny fluid tomorow and add in some of that gm syncromesh stuff or redline transmission fluid.

Coles notes: Car pops out of 2nd gear when upshifting from 1st and downshifting from 3rd when the car has been driven for a long period of time and is hot. What should I do to fix it, and what could the problem be?