alright. a week or two ago i was just drivin along and i happened to glance at the temp gauge and it was about 2mm from the overheated reading. i watched nervously and suddenly it just dropped right back down to the middle. i always watch the gauge now and it just goes up to the exact same mark and drops back down..over and over and over... sometimes it jumps up like a rocket and just stops right before the overheat line. then comes back down. im lost...any ideas?