I am trying to sell my 97 prelude and it is failing the CA smog test. It fails at idle but passes fine at 2500rpm. Below are the numbers from my test. These mean nothing to me so if anyone could help me figure out the problem I would appriciate it.

Idle:
RPM: 510
CO2%: 14.7
O2% : 1.2
HC (ppm): 375 , this is where it failed, max is 100
CO%: 0.38


My HC measure at 2500 rpm is down at 25 with the max there being 130. It was suggested to me that there might be a misfire. Any suggestions welcome as I don't want to pay hundreds to a mechanic so I can sell my car. Thanks