Oh ok, yet one more time where I shouldn't assume. Most folks I figure would use vacuum advance, but if you're not using it and you're still making max advance, I'd just make sure the weights and advance plate moves free and smooth.
This may be a bit of a dumb question, but it is taking off in first, right? I had a problem with my wife's Mustang once. It has a sticky accumulator piston in the housing and it wouldn't downshift to first when you come to a stop. The car would still take off, but it was actually starting in 3rd gear, so the car felt like a complete slug and somewhat resembled your description for the lack of stall and poor performance even though the engine ran fine.