I have a FSM for a 98. It has good diagrams of the purge system. My purge canister was crushed in the rollover, so I fabbed up a system using the 94 canister. The VSV's click on and off rapidly and do sound like pinging - maybe that's what you are hearing. This could also be the cause of your idle/surge issues.

I can scan the pages and post/email them to you.

94 4Runner, 5VZ-FE, A340H