High HC and CO at idle are due to an extremely rich air/fuel mixture, and the usual starting point is to check for a leaking injector or excessive fuel pressure. When the HC and CO remain high at 2500 rpms, you start to inspect the intake path for obstructions, like a clogged air filter. Did they only give you a two gas test? Most machines these days do 4 gasses, and have them all posted. I could tell you a little more if you could post the measurements of all 4 (HC, CO, CO2, O2). BTW, if you have been running your engine this way for very long, your new cats are going to need to be replaced. An exhaust rich enough to post numbers like yours will clog up a set of cats in a matter of months, maybe sooner.
Take care
~Chris
------------------
Retired Moderator
MustangNet
My site:
JimPorterRacing
RACECAR spelled backwards is RACECAR
HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!