code 44

ses light came on this morning, got it scanned, came up code 44 o2 sensor reading lean exhaust.. and was having way bad idle upon startup kept dippin to 500 or less, and bouncing back up to around 1-1.5k.could this problem be from running a fuel system cleaner(b-12) has never happend before when i have used it...... the o2 sensor is under 8 months old replaced it when was having problems with egr which was replaced(4th time) and finally working right... its 305 tbi, has new tps, recent tune-up.... might need to replace iac too, but not sure on where its at, a pic would help or a good description on where its at and to switch it out.

Replace the O2 sensor, and this time don't use an over the counter Bosch sensor.

i will be replacing the o2 this weekend. since i have been having a bad idle problem for a while, would idle bad and sometimes die; that was after it had been driven for a while and had time to sit & cool.
is it hard to switch it out?

is it hard to switch it out?
Naaa, just do it with the engine/exhaust warm (not hot) and use either the O2 sensor socket or a 7/8" box end wrench.

guess i should have been more clear on that, i know the o2 is easy, was asking about the iac if it was hard to switch out? the o2 as easy to get out as a spark-plug... is the iac the 1 thing on the back pass. side of the tbi unit with the wire comming out of it?

I don't remember exactly where it is located, but I believe the IAC is on one of the sides of the throttle body and should look something like this:

http://z28boy.cz28.com/pictures/tbi-iac.jpg

http://www.sierrajeep.com/images/Howell/How-TBI%20on%20bench.jpg this is good pic of tbi unit, i know the botton left on the tbi is the tps, is the iac the big bolt lookin thing behind the tps? and after i take it out before i put the new one in, should i maybe spray some carb cleaner in it to break down any build ups inside?