I have a 2005 pontiac bonneville GXP and I'm having issues with the idling. It keeps stalling out, on a cold or hot startup. It barely holds at about 500 rpm, dipping below and then stalling out. My first guess is the IAC sensor, and I ordered the part to replace. I tried disconnecting the MAF sensor and starting it, but it wouldn't start at all. I was told if it started but ran rough, then it would need replaced. I don't know the error code either, because I'm worried about driving it to get it tested. If it ends up not being the IAC sensor, what should I check next?

hi, scan tool info would be of great help - you can see tp, maf, map, ect, o2 sensor volts and fuel trims in real time - much easier and faster to diagnose - dont throw parts at it until you narrow it down- so I think its worth the trip - or for just a scan, maybe they can bring the tech2 to you. call around

how is the performance other than idle stall? how are plugs/wires

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poverty forces one to do unorthodox things

2000 SSEi
past rides:
1996 SSEi
1992 GTP
1987 Grand Am

Without more specific info, like DTC mentioned above, this is just to vague. It could be about 100 things causing this.

- Could be MAF (did you reinstall it the right direction?)
- Could be IAC
- Could be TB
- Could be bad plug(s)
- Could be bad coil module(s)
- Could be fouled plug(s) (oil/coolant... Headgasket/studs and coolant ARE issues on N*'s...)
- Could be bad ignition feed
- Could be bad injector(s)
- Could be bad injector feed
- Could be plugged intake
- Could be post MAF intake leak (This will definetely throw a code)
- Could be something in the EVAP system
- Could be bad fuel feed
- Could be in the exhaust... Bad cats

I could go on and on... But if it has the CEL on, those codes are paramount on telling us where to go. We can't just go "yea, it's your rotator splint..."

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Retired Bonneville Owner and former GM Tech:
2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*

Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2019 Chrysler Pacifica Limited: Mommy's new RGC
2015 Chrysler Town & Country Limited Platinum: Kids new RGC
2007 Chrysler Town & Country Limited: Sold to neighbor
2009 Pontiac G8 GT: L76, Sport Red Metallic
2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... new plow truck
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck

Welcome to the forums.

If you have another car or can get a ride, you can go to an auto parts store and pick up a basic code reader which can help you narrow down this issue. Without it, you may waste tons of money replacing this and that part until you happen upon the problem.

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-Car Guy Carl
"Penelope" - 2003 SLE - 247k Miles
"Sydney" - 2000 Honda S2000 - 98k miles