Idle problem until warm

[cdunc24]

I live in central texas so it doesn't get cold here but starting last Jan until about April and now again once the overnight temps started getting to the 50's or so the Yukon will idle up and down about 1000 RPM's (+/- 500) and almost shut off sometimes. This will happen the entire first trip of the day, if I drive 10 min. to the store or 20 min. to work it will continue. Once I shut it off after getting warm and restart it everything is fine usually till the end of the day. I don't want to spend alot of money repalcing crap if not needed. My first thought was O2 sensors but it stopped doing it over the summer. How would outdoor temp. affect them?
Any help is appreciated.
2002 Yukon w/ 5.3L 4WD about 96K miles.

 

[oomindwarpoo]

Fuel pump?

 

[JKmotorsports]

A small vacuum leak via the intake manifold gasket will cause a rough idle when cold until the heat expands it and seals the leak. Also check the air bypass passage in the throttle body. This gets full of gunk over time and can cause the same problem also.

 

[cdunc24]

thanks, i will check those out.

 

[chad_towns]

Man, mine is doing the exact same thing. Engine revs high for like twenty sec. and the goes into stall mode. Is the suggested repair someone fairly new can do?

 

[btrftw]

Probably a leaky gasket. I have the same problem and I'm pissed b/c i dont feel like doing this when its 11 degrees out.

 

[btrftw]

i changed the iac, and the coolant temp sensor and even cleaned the throttlebody. same issue...

next i'm doing the fuel filter, and plugs, if thats not it i'll be ultra pissed.

 

[jweezy]

i changed the iac, and the coolant temp sensor and even cleaned the throttlebody. same issue...

next i'm doing the fuel filter, and plugs, if thats not it i'll be ultra pissed.

I have a 2007 Tahoe,
fuel pump in tank, filter NON Existent
in the tank there is a Fuel Screen, runs terrible 51,000 miles
Cleaned all the throttle body Injection system Regularly with Professional Cleaners/Sea Foam Products,Can/Spray/Deep Creep, still runs like crap at IDLE, RPMs Fluctuate - Can't get it to Code. I'm going to try changing the Plugs even though they are 100,000 mile Ac Delco Iridium Plugs.

 

[ddteeters]

I heard it's the throttlebody?


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[DanielP]

Try cleaning mass air flow sensor if there's not a gasket or other vacuum leak. When engine is cold it plays a greater role (sole role in some cars) in determining air/fuel ratio. When engine is warmed it enters closed loop and AF ratio goes off O2 sensors. A dirty MAF sensor will not accurately measure air flow so engine will run too rich or lean. Not sure if these have MAP sensor but those also play a role in open loop AF ratio in some vehicles. An oil sprayed air filter will cause MAF sensors to require more frequent cleaning.