Toyota Repair: 2000 Toyota Rav 4x4, automatic, throttle position sensor, toyota rav

Question
The RAV has approximately 30,000 miles.  Car starts and runs fine but the RPM of the vehicle is unstable it lowers to approximately 600-700 and then it goes up and down roughly 50-100 rpms or so.  More than anything it is annoying and I know that it should run at a steady 850-900 when in park.  I've changed both O2 sensors because the engine check light came on two months ago and I hooked it up to a hand held computer that read a code related to the O2.  I've changed the spark plugs, I only put premium gas in it, air filter is new, and I've bought but haven't put in yet a new fuel filter.  I've researched parts and I know the vehicle has a throttle position sensor, an air/fuel mix sensor and an idle speed control valve.  What are my options?  I've read your responses for other vehicles and they have been very helpful.  I'm in Honduras and so getting quality mechanical assistance is a bit of a problem.  Thank you.  

Answer
The problem is very common, it's the idle speed control valve, remove the entire throttle body and then remove the idle speed control valve and clean it with a throttle body cleaner, at the same time clean the throttle body using a soft brush and the cleaner, reassemble everything and the problem will be solved.