Join Date: Oct 2007
Location: NC, USA
Car: 1999 Subaru Legacy Outback 2.5
Feedback Score: 0 reviews
Have the valves ever been adjusted on this car? Check the maintenance schedule and it will state the valve adjustment needs to be checked and adjusted as needed at, I think, 100k miles. I own this same model with 172k miles, and the engine, over time time, developed a tick that was resolved when the valves were adjusted.
As already stated, the idle is controlled by the IAC, and should never be adjusted unless it has just been replaced. Check for a signal at the IAC from the computer. If the signal is arriving at the IAC, the IAC may be bad.