maybe irrelevant, with your shiny new SMOG check, but...
What is the idle vacuum? Is it below about 18"? (Check that spec).
IF the vacuum is normal, and I believe that number is close, the MAP sensor may be providing a low number to the ECM, telling it the throttle is open more than it is, and the ECM adds fuel, as it does under acceleration. I'd test the sensor and the following first, though.
At 158k, the throttle body shafts are probably loose, from wear in the TB holes, being a rather soft metal. Years ago, I bought a kit, with a special drill bit and brass bushings to drill the shaft holes, then re-bush them. I have that bit somewhere, if you need it. This kit was not big dollars.
The TB gaskets may leak air, too.
To answer your other question, the TBs, however simple to teardown and rebuild, are a bit finicky to get exactly right. Having done this rebuild a few times with mixed results, I would have a pro do it next time then have them properly synchronized. BTW, I too, find Holleys simple, especially compared to Carter or Rochester carbs.
The AIR system initially injects air into the exhaust manifold, to assist combustion on a relatively rich exhaust. At the CAT and the engine warms, the SMOG pump air is then diverted into the CAT, for the same purpose. The idea in delaying air injection is to allow the CAT reach its operating temperature as quickly as possible. Under certain conditions, the air is diverted to a vent, reaching neither CAT or manifold. I'd have to pore through the manual to relearn when air is vented.