I'd read on Brickboard that an often overlooked cause of poor performance is a clogged fuel filter. I'd been experiencing poor power, but I'd checked my filter and it looked clear, so I didn't suspect it was a problem.
Given the fact that fuel filters are less than $3 at the local auto supply (Fram G4164), I figured it couldn't hurt to get a new one. I was glad I did. After removing the old filter and comparing it to a new one, I realized it was dirtier than I'd thought.
notice the dark matter at the bottom of the old filter
While I was at it, I decided to throw an extra filter on the line before the fuel pump and change all the fuel lines (5/16" from the tank to the fuel pump, 1/4" from the pump to the carbs). The old lines, it turns out, were getting pretty hard. Total cost for filters and lines was under $10. Inexpensive fixes that I hope will prevent future problems.
filters before and after the pump, new lines and toothless hose clamps all around