With only the vacuum advance (?) used from the throttle body ( cap over the bottom vacuum pipe / tube ), is that corresponding (retard) tube on the distributor left open while timing ?
I ask because the car still stumbles when cold, start and go in 60 above temps. Wondering if timing is advanced from plugging both vacuum lines, 2200, copying '79 procedure when the '81 uses only one vacuum line.
I know, go try things. Just posting for a sneak preview.