My 1994 Mercedes E320, 3.2 L recently failed VA vehicle emission test for the second time. It failed on HC ppm @2500 RPM reading 279 limit 125 and on HC ppm on idle reading 145 limit 125. It passed both CO % 1@ 2500 RPM reading 0.64 limit 1.0 and on idle reading 0.34 limit 1.0 and Dilution % at 2500 RPM 14.72 and idle 14.81. Overall it failed. What could be causing high HC ppm? Suggestions/advice/or pointers?

Thanks!

Pete2