TOM LARSEN'S DAY GOT interesting when he left the seminar on blowout prevention at Southwest Research Institute in San Antonio and headed for home on the Gulf Coast. A beat-up Crown Vic started tailing him so inexpertly that the only experience the driver must have had was watching bad spy movies. Not without his own resources, he managed to subdue the two bad boys but let the driver-an apparently uninvolved young lady-get away. After a few threats...