Maybe four Solenoid Valves?
Vacuum Solenoid for early (90' under Plenum).
Vacuum Solenoid (filter) for Later (95' under Plenum).
...............Solenoid for Charcoal Canister (91'-95' under Plenum).

Solenoid located on Charcoal Canister (not shown) under Drivers Headlight (90').