I have a 1999 Ford Ranger 3.0 V6 that throws a P0442 code (EVAP small leak) about once a week or so. I replaced the gas cap and cleared the code, but check engine light came back on after about a week. I have checked system for bad conections, etc. Code came back on after about 10 days after clearing code the second time. Any ideas as the most likely place to look first? Thanks.