acceleration problem

[Art Pfenninger <ch155@FreeNet.Buffalo.EDU>]

        Does anyone have a suggestion why a 77B with a ZS carb would
suddenly develop a problem with acceleration? I can get the car up to 70
but it is running like a dog. Plugs, wires,cap,rotor new last year.
Cleaned the plugs(the car runs rich), vacuum lines ok compression ok,
vacuum ok. Looks like timing is retarded at least according to the vacuum
test however nothing is different then before the problem started.
Replaced the diaphram which was bad but the problem still exists???
...Art