Did they give you a print out of the whole range of gases? What's the whole range? Was there anything else it was high on? I doubt it's the TBS unless you were border line to begin with.
First have you checked to see if there were any CEL codes stored in the PCM? Have you checked the CCV? That gets clogged easily. Depending on what the other reading are you could have a number of things. Low fuel pump pressure, partially plugged injectors, a vacuum leak, or defective O2, MAP, ECT, or IAT sensors. A lean air-fuel ratio causes high NOx, high HC, high O2, and low CO and CO2. Also a Bad thermostat or improper one could cause similar problems.