95 s-10 w/4.3 idles erratic up and down.already cleaned the egr valve.

Sounds like a vacuum leak..this is the 4.3 with the TBI setup correct...Its probably going to be one of the main vacuum lines in the front.

Another thing...tap the IAC with a wrench or something like that and see if the idle smooths out...

if that doesnt work . . .  check the second 02 sensor
Your not throwin any codes are you?    ( check engine light on?)

The 02 sensor wont cause an irratic idle, just a decrease in fuel mileage..maybe running rich at idle.

My second o2 sensor is bad. .   and  it idles hella low. . . like  everywhere from 750 to 250. . .         just a suggestion

Yeah id agree but i dont even know where the o2 sensor is


and please dont bother explaining it

2nd 02 sensor....as in the one after the catalytic converter..that only tells the computer if the catalytic converter is there and is doing its job..has nothing to do with a/f ratio control or any actual engine function.