Hey there...I'm hoping you can help as I am about kill myself.  Rosa (the
bus) is a 1987 GL with 181k miles.  She exhibits the following symptoms:

Cold Start-Sometimes starts first try but usually takes 6-8 tries to get it
going.

Hot Start-Always takes 8-10 tries.

Cold Running-Idles fine without load.  Driving idle will occasionally drop
down to 500 rpm where it will sometimes catch and continue to idle at 800
rpm or stall.  If it stalls see Cold Start above.

Hot Running-Runs great on highway but will occasionally buck and backfire.
Last year this bucking and backfiring was rare and turning the bus off and
then back on cured problem for another couple of months.  Now the bucking
and backfiring occurs daily.  Also surges, but this doesn't result in
bucking and misfiring just annoying unevenness.  If Rosa bucks and we
restart, see Hot Start above.

Work Done:
Temp Sensor II-Replaced last fall and helped idle problem for a while.
Idle Stabilizer-Replaced to last fall to cure idle problem (unrelated).
AFM Harness-Replaced Saturday in attempt to cure intermittent bucking.
AFM Wiper-Cleaned with wiper with contact cleaner and cleaned inside of AFM
with carb. cleaner.
Throttle Body-Cleaned inside carb cleaner.  Check for vacuum leaks-none
apparent.
Newer-Plugs, wires, distributor cap and rotor.
Newer-Fuel pump (unrelated) and fuel filter.
Newer-Coil (DPO)

Plugs are a nice tan color no deposits, gas mileage within specs, passes
emission with flying colors (CO mix).

So if you have any ideas on how to help me and Rosa (the bus) out we'd
really appreciate your time so we can get back to our summer already in
progress!

Chris P.
Seattle, WA