P0505 IDLE AIR CONTROL SYSTEM\r\n1998 Toyota Land

You have a few different things coming up as these lights and codes. I'll list the code meaning below.
Did you mean the VSC light? VSC, Traction Control and ABS all refer to your braking system so get it fixed AS SOON AS POSSIBLE!
The '505' code refers to the air flow management system in the air intake manifold. The other codes refer to the EVAP system on the vehicle. This may seem a silly suggestion but check you fuel filler cap isn't loose, missing or the seal on the cap isn't damaged. The EVAP works as an air tight system and if it is leaking that is one of the most common causes, (and its a cheap repair).

P0441 = Evaporative Emission System Incorrect Purge Flow
P0455 = Evaporative Emission System Leak Detected (large leak)
P0456 = Evaporative Emission System Leak Detected (very small leak)
P0505 = Idle Air Control System

P0505: Idle Control System Malfunction. The computer controls idle through the idle air control motor or valve. It would be mounted on the throttle body assembly.

P0505 should be the IAC (Idle Air Control) System Malfunction

Hope this helps

Code 505 is for a problem with the idle air control system. The computer can not control idle speed.

Error Code: P0505
Fault Location:
Idle Speed Control (ISC) System - Malfunction
Possible Cause:
-Wiring harness.
-Idle speed control (ISC) actuator/Idle air control valve (IAC) valve.
-Throttle valve tight/sticking.
-Engine control module (ECM).

P0505: Idle Air Control Valve System fault, Code P0505
-Vacuum leak
-Dirty throttle body
-IAC motor defective
-Poor electrical connection to the IAC valve, hope this helps and good-day !

P0505 Idle Air Control System Malfunction That points to either an unplugged or bad Idle Air Control Valve (IACV).

P0505 Idle Control System Malfunction

IACV or Idle Air Control Valve if equipped is malfunctioning.

P0420 Catalyst System Efficiency Below Threshold (Bank #1)
The Catalytic converter is not working up to par in Bank#1.

I think this will point you in the right direction..

P0505 is correct, but replacing the IAC won't help if the PCM cannot control and/or monitor the operation

you need to measure voltage at the IAC and/or the signal return to the PCM

does yurs have the idle air control motor if so look into that