When I moderately decelerate to slow speeds in 1st or 2nd my van
bucks and jerks. I have adjusted the idle switch "by ear" and it appears
to be working (the switch near the throttle cable/air flow meter).

There are two more idle control items (idle control regulator and the
electrical component behind tail light - not sure of the name right now).
Should I check or replace these?

Is checking idle components even the right thing to do?

What else could it be? It's very annoying.

Thanks and aloha,

Gordon