O2 Sensor?

ok... a 90 2.2L Chevy. the idle comes way up then it comes down very slow on startup and every once in a while the engine stalls. the check engine light come on rarely and only stays on for a minute or 2 then goes out. i checked the plugs and they were WHITE. really bright white. which tells me its leaning out WAY too much. my question is... would a bad O2 sensor cause the irradic idle? it has a new TPS, IAC, EGR valve, and crank position sensor. i bought brand new plugs and put in it yesterday. and it has new plug wires and i checked the ignition system and all that is good. about the only thing left is the O2 sensor but thats been changed about 6 months ago and i know that sometimes they dont last very long. thanks for the help guys, i appreciate it...

• First of all, the O2 sensor isn't even being read by the computer until the engine is fully warmed up and after a certain period of time, so I doubt it is the problem.

• Could also be a bad coolant temp sensor OR THE WATER LEVEL IS VERY LOW. CHECK THIS FIRST!

• Check for a vacuum leak in the manifold or throttle body area which will cause a high idle.

• You could also have a bad electtrical connection in the IAC motor wiring, causing intermittant idle speeds.

• Could also be a sticking throttle cable.

Let us know what the fix is.

pertaining to the O2 sensor....

even if the O2 sensor voltage is fluctuating extremely, like going up all the way and dropping below operating voltage?