The floating down to idle could easily be loose springs on the advancer allowing the timing to stay advanced longer than it should, which always contributes to the problem of returning to idle properly. Be advised that pod filters on CV carbs are often next to impossible to get tuned properly, and many get tired of chasing it and give up. The bike was designed to use the complete intake tract that came with it from the factory for best all around performance. These engines are more sensitive to small changes than, say, a car V-8 where changing an air filter or plenum chamber has far less effect running through a single carb or throttle body feeding multiple cylinders. And, you should consider shopping around for
all your parts, those guys in Houston might be convenient but they mark up their parts more than any other supplier we know of. Here's a great example, the solid state rectifier/regulator combo unit we recommend to replace the separate rectifiers and regulators on these bikes are likely from the same manufacturer that those guys in Houston buys them from - but you pay $65 for it from those guys in Houston, and you pay $37.50 for it from Sparck Moto.
Sparck Moto - Modern Gear for your Vintage Ride
www.sparckmoto.com
https://www.those guys in Houston.com/honda-cb-cl-rectifier-regulator