HC is usually the result of a misfire, high CO is running rich.
Put a converter on it and you'll probably fix it. But the tune up stuff is a good idea if it's been a long time. A flaky wire, half fouled or excessively worn spark plug, etc can make HC go up a bit like you're experiencing.
In the old days, it was fun to watch the needles on my 1970s Sun machine drop when the cat warmed up. 90% reduction in HC and CO is typical, sometimes more.