1971 CB750 - Sluggish acceleration from stop.

[Jakevidio]

Problem started a couple weeks ago after a long trip.  When I'm accelerating from a stop, I have to really ease on the throttle otherwise it gets bogged down.  I've never done it to the point where it will stall, but it sounds like it could if I didn't let up.  Acceleration in second gear is a little better, doesn't bog down as much, but takes a little longer to pick up.  It's even better in third, and so on...  No issues on the highway, jumping around in 5th gear.  Again, it's ok when I'm just feathering it on, but if I hammer the throttle, bog city.
I think it started happening gradually when I started putting a little sea foam in with the full tank.  This is my third tank with the stuff.  Should I try my next tank without it, or is this just highlighting a bigger problem I could be having?
Anything else I should be looking out for?

[Re-run]

Yeah leave it out on the next tank.
Also, check your plugs and see what color they are.
You might be running too far on the rich or lean side.