Re: 89 camaro won't pass emission
hc is unburned fuel. I'd put a set of plugs and look at the wires/cap/rotor and air filter. Like a tuneup.
151 vs 148 is awful close, your friend who suggested driving awhile may be thinking that a good drive would get the plugs to self-clean. Which is valid. And that 89 will rip all the hide off your arms doing a set of plugs if it's like the 85 we had.
151 vs 148 I think I would ask them to show me the cal on their instrument. hc cal gas (span gas) is expensive and I bet they don't have any. The way I span mine is to soak a rag in gasoline and let her whiff it, it maxes the sensor and then I cal to the sensor max. This is absolutely a non-compliance level deal though. We are not regulated on unburned hc but use it as a troubleshooting tool.