Toyota Repair: 2002 Toyota Camry low idle speed, air intake hose, wire mesh screen

Question
June 7, 2008
God bless you.
2002 Toyota Camry, 2400cc, 2AZ-FE; 121,000+ miles.
Idle speed is too low, it often stalls. RPMs are bellow 600 rpm.
Recently replaced the spark plugs with the recommended iridium plugs.
Cleaned the mass air flow sensor; tested OK.
It still has the original upstream and downstream O2 sensors. On a scan tool both give correct graph signals.
About a couple months ago the catalytic converter, which is integrated with the exhaust manifold, was replaced, since it was giving frequent P0420 DTC.  The P0420 DTC has not reoccurred. The catalytic converter unit that is behind the referenced unit above was not replaced; car has good power going up hills.
Change oil/filter every 5/6000 miles; also use fuel injector cleaner additive at those intervals.
Should both O2 sensors be replaced due to the mileage they already have?
What else can be done to bring idle speed to specifications?
Additional question, does this engine have a PCV valve? Can’t locate any.
Need the circuit diagram to test the ignition coils.
When locking the car with the wireless transmitter the horn blows 3 times. Can’t make it to just click.
Thank you for any assistance you can provide in resolving these matters.
Cordially, Otto – enlcptipr@yahoo.com  

Answer
It doesn't have a PCV valve and even if it did it wouldn't be the problem, the problem is that there is a lot of carbon built up inside the throttle body, I have fixed many idle problems on this engine by just removing the air intake hose and cleaning the inside of the throttle body with some air intake cleaner and a stiff brush, there is a wire mesh screen on one side be creful not to damage it, just clean the other side and the throttle plate, block the plate open so the throttle body can be cleaned past the plate. This should take care of the idle problem, the engine will not restart real easy so open the throttle about halfway on restart to give it enough air to start up, rev it up a few times to clear it out then drive it right away through a few stop/go cycles, if for some reason it idles to fast now, remove the negative battery cable and wait 10 seconds then reconnect and drive it again.    
The horn sound can be turned off if it's the factory keyless entry system but it will require the factory scantool to be connected, if it's not factory OEM keyless entry then any alarm installer can help.