Note that this is a vacuum retard - not advance. Vac is there at idle. If you turn on the AC for example, it switches the solenoid and there no longer is vac, and your idle increases as timing advances.

Define your hesitation - going along and it just starts to chug? Low power? Flooring it doesn't go anywhere? Or it seems like it won't go, and then it does actually go?

If it's the first group I'd suspect fuel supply. If it's the second one, where it hesitates and then takes off, I'd suspect the throttle position switch.