Mr. Bigglesworth the 2nd

I changed the air filter, oil, oil filter, and I am about to change the fuel filter, PCV, Spark Plugs and wires (these were last changes 1-1.5 yrs. ago), and PROBABLY the Cat Converter (I don't know how to do it, but I imagine it is not extremely hard, is it?) Here are the readings for both Virginia emission tests: @ 15 mph: HC ppm: Limit: 125; Reading: 20; Result: PASSCO% : Limit: 0.50; Reading: .73; Result: FAILNO ppm: Limit 1636; Reading: 376; Result: PASSRPM: Reading: 1777; Result: VALIDDilution: Reading 14.7; Result: VALID@ 25mph: HC ppm: Limit: 136; Reading: 44; Result: PASSCO%: Limit .73; Reading: .73; Result: PASSNO ppm: Limit: 1591; Reading: 282; Result: PASSRPM: Reading: 1802; Result: VALIDDilution: Reading: 14.8; Result: VALIDSomeone said I must change the cat. Any suggestions?I noticed that on the emission result paper, there is a part that says "Emissions Control System Inspection" and it lists the following: 1) Air Injection System N/A2) Exhaust Gas Recirculation System: PASS3) Positive Crankcase Ventilation System: PASS4) Catalytic Converter: PASS5) Fuel Evaporative System: PASS6) Themostatic Air Cleaner System: PASS7) Gas Cap Pressure Test: PASSOBD Malfunctioning Indicator Lamp, Diagnostic Connector, Diag. Trouble Codes: N/AI forgot to mention that the Temperatur Sensor (o2 sensor?) has been already changed (was charged $150 by a mechanic... sounds like too much!) and this did NOT make the vehicle pass the test! I don't know what to do and I'm frustrated. Someone suggested I change the Cat, but on the emission test result it is listed as "Pass"... what should I do? Thank you!!!! Any suggestions will be highly appreciated!

Dirty Dave

Find someone with an engine code reader to find the problem. If you can't do that then be sure the gas cap gasket is OK. Then replace th O2 Sensor before you do anything else.