How do i adjust the idle arm on a buick century 3.3 1991 model because its ideling high

Not a mechanic but have heard similar from older cars and been told that the tappets need adjusting.

The idler arm would be in the steering section for a car with a steering gearbox.
Your problem may be a vac leak, or the idle air control valve is sticking open. The idle speed is controlled by the engine computer, so there are no adjustments.

Depends how fast is idle but it could be normal when a/c is on idle should raise and cooling fan on
hope it helps

You have a failed IAC (Idle air control valve) its on the throttle body,

The codes might have been handy to have but I would be looking for a vacuum hose that was damaged or inadvertently detached. Losing vacuum will cause a high idle.

valves are not adjustable torque rocker arms to 120 inch/lb then 30 degrees

Sounds like you have another Vacum Leak, What is this thing idleing speed AT...?????? Vacum Leak Cause high Fast Idel...so i would check futher into more leaks

IS IT FUEL INJECTED OR CARBURETED?

Sorry I spelled engine wrong. Anyway I removed the IAC (idel air controll valve) and cleaned off all the gunk and checked for freedom of movement. Re-installed and car now runs fine . Thanks for the intrest.

you should never have to adjust it, it is adjusted by the computer using the IAC (Idle Air Coltrol) valve.

Why do you feel that you need to?

if the idle is too high or too low then you have a problem with the car that needs to be adressed, not the idle