every thing checked out to be ok have no other ideas of what could be caucusing the idling problem

what kind of truck is it ? is it a 4.3 vortec engine?

oh i didn't see the 1st page .. hows the iac valve look?

it is new was a little dirty i cleaned it and put it back together and no change still wont idle not a single mis when reved

did you check your cat converter? got any ces codes?

I know i say this on alot of posts, but when was the last time ya changed the fuel filter? If it is starting to clog up from junk from the tank, it will cause less gas flow and more than likely cause the problem your having. I rec fixed a friends blazer and the gas filter was the problem with idling problems and surging. try that it only cost around $10 for a new one and its east enuff to do your self.. If your not familiar with where it is located its in the frame rail under the drivers side of the truck.. good luck.

there is no codes and how would i check the cat

The filter looks new but i dont know how long it was on there before i got it so i will change it and try that also

I got the blazer idling i unplugged the O2 sensor behind the cat and it start and idles what could that mean ? the cat need to be changed or should change the o2 sensors first then go from there

That doesn't make any sense. The post-cat O2 sensor is a catalyst monitor only... It does not have anything to do with engine operation.

ok that s what i was wondering but was not sure could that mean there is another problem that would cause that

Unless there was a problem with that sensor that affected the ground source for the upstream sensor. But that is out there...

What experience do you have at diagnosing electrical problems?