Toyota Repair: 91 ToyP/U 22re IDLE, intake hoses, airflow meter

Question
I have a 91 Toyota PU with a 22RE engine, Fuel Injected 5 speed with 235000 miles.  Recently the IDLE has become irratic at all times except under a load when driving.  It idles for example from 800 rpm to 1200 rpm then cuts back to 800 and back up.  

Its driving me crazy.  Is there a simple fix?

Thanks Patrick  

Answer
I assume there is not a check engine light on which means that there is a mechanical problem, it sounds like there may be a vacuum leak somewhere on the intake system, this is the most common cause for erratic idling.
Check the intake hoses that connect the airflow meter to the throttle body for any cracks or leaks, there may also be a leak between the intake manifold and the cylinder head, they are known to develop a leak at the gasket where the EGR valve bolts to the head, the quickest way to diagnose for this is to spray some carb cleaner around the area with the engine running, if the engines starts to race there is a leak and the manifold gasket needs to be replaced, let me know if this solves the problem or if you need more help.