1999 Isuzu Rodeo, high idle problem.

Po161 O2 sensor bank 2 sensor 2 after catalytic.

Ah 2 posts, now with some more facts.
is this USA car????? now with correct car name.
24valve valve what/? v6

Does engine get to normal operating temp? this is first.
always for ever and ever ! does it? 180F + is NORMAL
is it ? if not BINGO, see why?
the ECU run in 3 modes, cold ,warm,hot. so........
so , cant help you if you cant at least know temperatures.
you make this so hard, no known what is under the hood
asking me to lookup every 24v isuzu engines. pain.
my guess is V6 (4 x 6 =24)
which one, 6VD1 or D1w? not the GM engine but a real ISUZU
V engine, 6vD1, and that matter for fueling and well, ALL that.
3.2L or 3.5 , in 1999.

P0161, is O2 bad or wires to it.
bank2, sensor 2 heater is burned out, easy no>?
and not your idle reasons.
now 442

- Missing or loose fuel cap ??????????????? bingo?
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking
again not cause of high idle.
so how long was the CEL glowing, for years?
ignore 442, or make gas cap tight.
ignore 161, its not used for FUELING ever.
so again, back to square one

1. what country USA? or Canada?
2. what engine, 3.2 or 3.5 V6, always know this for 100 time better help,,,, no really.
3. is engine reaching 180f coolant temp or not.
4. if it is, they you have vacuum leaks (complex topic that i do not cover here any more,,,, )
5. ISC stuck open, or iAC stuck open from gunk in the valve.
6. throttle valve stuck open with gunk or no slack in cable.
7. more, lots more why not get a shop in the loop.