Actuator Test
WARNING: This page is about a different car, the 1992 Subaru SVX, 1992 Subaru Legacy, 1991 Subaru Legacy, and 1990 Subaru Legacy. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect vacuum hose from actuator. Apply vacuum to actuator with a hand-held vacuum pump. If throttle does not fully open, replace actuator. If throttle fully opens, disconnect vacuum supply from actuator. If throttle does not close, replace actuator. If throttle closes, actuator is okay.