92 3.1l cutlass idle and stall problems

I am working on my mother’s car because she has no money to keep in running, so I am footing the bill. I recently replaced the fuel pressure regulator, when it went bad it filled everything full of fuel. Know I am having idle problems it stalls at idle in drive after you press or release the drake (seems to be worse when you let of the brake). It also idles a little rough, I have replaced the spark plugs and I read the codes 1. Unable to control idle 2. o2 reading lean 3. o2 response fault. I have checked for vacuum leaks by spraying carb cleaner around the intake and vacuum hoses and have not found any yet.
I have checked the IAC and it checks good with the ohm meter.
Should I replace the o2 sensor next or the IAC.

Thanks in advance for any help!

the codes were 044, 035, 013

code 44- lean exhaust detected
code 35- Idle Air Control Valve or circuit
code 13- Oxygen Sensor

since your car is a 92, i suggest replacing the 02 first, disconnet the battery terminals for at least thirty seconds to clear codes, and then drive the vehicle at various speeds to allow it to relearn.
did you compare ohm readings to spec? more information needed here. Have you confirmed the IAC is operative?
Chances are the 02 is contaminated, but have a look at the wiring associated with these to items as well. trace them, find out the values you'd expect to find at the PCM compared to at the wires connector. It would be ideal to verify both circuits before throwing parts at it... whatever you do, this one wont be to hard for you to solve. Make sure you re-post your fix!! good luck

I replaced the o2 sensor and that fixed the problem runs like great know and no more stinky exhuast. The guy at Orielly auto parts said they are very common, they stock like 9 of them at all times.

Thanks for the help!:)

sweet... you know, 02 sensors are not often thought about as an item that needs attention.... what i mean is, they don't fail all of a sudden, even though it might appear that way... they become less and less capable of doing the job they were designed to do over time...until they reach that threshold... especially in older cars that tend to have more contaminants in the exhaust stream. I replace my 02 sensor every 30 thousand for peak performance.