Engine stall at low RPM

I own a Toyota Camry LE 2.2 1993 and I am experiencing a ghost problem. The engine stalls at low RPM and it may take many time before start again,or not. The most probable cause is the IAC valve where the magnetic relay is almost burning while engine running. I checked all over the Toyota Forums and there are many cases like mine and they covered EGR,VSV,TPS and many more, so far I am not sure what can really being happening. On my car looks like the fuel pump, fuel lines in/filter/return and vent are fine, also the spark plugs are good too. Curiously I found spark plugs on cil 3 and 4 almost floating in oil probably spill during refil and all 4 spark plugs are showing a health brown color at spark points. I would appreciate some help to can solve this nebolous case.