The manifold hookups are for the charcoal canister purge on the left side and the fuel pressure regulator, with one tee-ing off to the vacuum reservoir on the right side.
The vacuum advance on the distributor hooks to a nipple on the bottom side of the throttle body, where the vacuum signal is ported by the throttle plate. If this nipple is unused and/or your vacuum advance is hooked up to manifold vacuum, it could explain your miss (lean condition and over-advance).
Gregory Smith
'87 Bertone X1/9 Corsa
'88 VW Vanagon
Olympia, Washington, USA
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