I've had my '73 240z for a couple of years and its always run pretty decent, but it overheats in city driving. Last fall I was driving and hit some rush hour and it got pretty hot (about 3/4 of the gauge). After a while I got out of traffic and it started to cool down some, but about a mile from my house it started running really rough and 1/4 mile from my house it died completely. I coasted downhill to my house and pushed it into the garage. It wouldn't start, but I was so tired of the ove