Trouble with start up...

I have a 2002 Pontiac Grand AM (3.4L 6 cyl) and for the past couple months the engine will not turn over unless I'm giving it some gas. I'm pretty sure it's due to the fact that it was flooded pretty badly back in July but we turned the engine over by hand to drain the water, have been replacing parts as needed (rotars, bearings, etc.) and now I'm onto the sensors...which is where I think my current problem lies. The weird thing is that my 'Check Engine' light came on, had the diagnostic test done and was given code P0507 for High Idle/RPM. But then I replaced my starter and through that process the battery was disconnected for a long period of time and the 'Check Engine' light was no longer on after that. I've been waiting for the memory to pick up on the problem again but it's been a week and nothing. So now I'm left wondering...is that sensor even bad? And if it is, is the high idle the cause of my problem at start up? To elaborate more, when I start my car (generally only happens when engine is cold) it will idle spuratically between 500 and 1200 RPM. If I dont give it some gas til it's warmed up it'll die on me. It's like it can't maintain an idle above 500 RPM at most. And this actually happened in the past where I have to drive for about 30 miles or so keeping my foot on the gas while braking because as soon as I let off the RPMs drop to 300 or less and my car dies.

Sorry the message is so long....please help!

By the way, if it makes any difference, I've already replaced the oxygen intake sensor.

Welcome to AF !

Could be a few things going on here.
PO507 is the idle control, which to me would indicate the IAC(intake air control) is dirty/plugged up or its bad and not showing a code.
It is located on the right top side of the throttle body(TB).
It can be removed with a torx bit and cleaned with TB cleaner to see if that helps with the idle.
Dont push or turn the end if you remove it.


The surging you described could be the IAC,
though it could also indicate thiers a vacum leak on the intake manifold somewhere.
You might here a whistling noise when the motor is running if its a bigger leak.

Hope that helps !

Thanks for the info...I'll def check the IAC, that's kinda what I was thinking it was but when I went to Autozone with the code they had like 10 different idle sensors so it made me second guess myself. As for a possible vacuum leak, I already checked that out so hopefully it's the IAC.

Thanks again!