My car idles high in park and neutral. Could it be valve adjustment is needed? on 1991 Toyota Celica

The rpm gauge is busted but the idle is high in park and neutral. It also surges (goes up and down) a little when at red lights. I have replaced the throttle position sensor and the idle air control valve(new parts). A mechanic also replaced the timing belt because there was 100,000 miles on the engine. I read that It is a common problem with this model car-the valves needing to be adjusted. I just wanted to know If valves could be causing it? I have not checked for vacuum leaks or proper grounding of the two replaced items(iac & throttle sens). I cleaned the throttle body/IAC with throttle body cleaner. Google searches keep pointing to things I have addressed. Any ideas? I'm also getting a 51 obd I code but my AC works fine.

by in Memphis, TN on May 14, 2012
1 answer 2 comments
ANSWER by on May 14, 2012
Sounds like your idle air control valve,removing and cleaning may work but you probaly have to replace it.
COMMENT by on May 14, 2012
If you read more then the title you would know that I have already replaced the IAC valve with a new replica. I'm looking for alternative solutions!
COMMENT by on May 14, 2012
Sorry ,when i clicked on your question all it showed me is that you had a problem with your idle,vaccum leaks could definetly could cause your problem,leaks at the intake manifold,i just switch an intake gasket on a 95 accord and it solved the problem,removing the intake and cleaning the inside with a coat hangar and carb cleaner could help.i have never seen valves cause this problem but adjusting them cant hurt,they need to be after 100,000 miles.