I have a 90 subaru loyale and has a rough idle while sitting which sometimes idles fine and other time just get rough jumping around 600-1000. I have replaced timing belts, spark plugs, rotor and cap, IAC, and fuel filter. Wondering if anyone has any ideas?

Fuel injected or carbureted?

My '89 DL wagon has similar symptoms. When I get the interior sorted, I'm going to look for vacuum leaks. 

 

John

Fuel injection, the thing runs fine while driving

Check for vacuum leaks around hoses and the intake gasket. With mine I have taken the strategy of just replacing the 20 yr old vacuum hoses on principle. They are rubber and will deteriorate over time. They are not expensive and saves me having to chase down piddly little leaks in hoses that cost 75 cents to replace.

Yea ill give that a try, the thing does have 460k miles on her and still going pretty strong besides this lil problem