Trailblazer stalls at stop in drive with AC on.

Any recent engine repairs ? Trouble codes ?

on mine was the pcv valve line broke and the valve line to the fuel regualator jus put right size rubber hoes on it and was fixed doesnt stall now if still stalls the hose you put on isnt tight enough and leaking air has to have good air flow so check all vaccum lines if still stalls

It can be low fuel pressure issue or clogged fuel pump.Or its engine related issues,---------------
Check the help link mentioned below to troubleshoot the problem :------

Engine stalls when gas is given?

http://technoanswers.blogspot.in/2012/01/engine-stalls-when-gas-is-given.html

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Car stalls when MAF sensor is connected?

http://technoanswers.blogspot.in/2012/01/car-stalls-when-maf-sensor-is-connected.html

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Car Engine Stalls While Driving?

http://schematicsdiagram.blogspot.com/2011/12/car-engine-stalls-while-driving.html

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Car stalls and throws white smoke from exhaust?

http://repairhelpcenter.blogspot.com/2012/01/car-stalls-and-throws-white-smoke-from.html

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Stalls And Dies At Stop Sign?

http://www.howtobyme.blogspot.com/2012/07/stalls-and-dies-at-stop-sign.html

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GMC Sonoma Stalls and idles low

http://technoanswers.blogspot.com/2012/10/gmc-sonoma-stalls-and-idles-low.html

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Nissan Pathfinder stalls and bucks on Acceleration?

http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html

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1992 Chevrolet stalls and shutdown?

http://schematicsdiagram.blogspot.in/2012/04/1992-chevrolet-stalls-and-shutdown.html

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Stumbling and stalling at idle after engine rebuild?

http://schematicsdiagram.blogspot.in/2012/03/stumbling-and-stalling-at-idle-after.html

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1990 mazda 323 stalls and quit running?

http://technoanswers.blogspot.in/2012/02/1990-mazda-323-stalls-and-quit-running.html

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2000 Toyota Camry: Idling and Stalling Problem?

http://whatisbyme.blogspot.in/2012/05/2000-toyota-camry-idling-and-stalling.html

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1995 Toyota Corolla: Stalls, Sputters and Pops Through Intake Manifold?

http://whatisbyme.blogspot.in/2012/05/1995-toyota-corolla-stalls-sputters-and.html

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1999 Toyota Camry: Erratic stalling and high engine RPM at idle?

http://whatisbyme.blogspot.in/2012/05/1999-toyota-camry-erratic-stalling-and.html

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Dodge Dakota stalls, stumbles at idle. Has low fuel flow and runs hot?

http://schematicsdiagram.blogspot.in/2012/03/dodge-dakota-stallsstumbles-at-idlehas.html

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1994 Toyota 4Runner: Stalls and Stops While Driving?

http://whatisbyme.blogspot.in/2012/05/1994-toyota-4runner-stalls-and-stops.html

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1997 Toyota Camry: Erratic Idle and Intermittent engine stalling?

http://technoanswers.blogspot.in/2012/04/1997-toyota-camry-erratic-idle-and.html

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Ford Maverick: No Idle and Stalling issues?

http://schematicsdiagram.blogspot.in/2012/04/ford-maverick-no-idle-and-stalling.html

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These details will help.
Thanks.

Your idle timing may be off a little. Have the timing checked.

if this happens while the defrost of ac is turned on, it could be a seized ac compressor which will cause the serpentine belt to squeal and drag making the engine sometimes stall. if it happens with the ac off and the selector on say the floor, or dash vents, the issue could be a bad alternator and battery. this is confirmed when the blower motor engages and the lights dim and then the truck goes dead.

check fuel pump pressure or clogged fuel filter

check throttlr sensor

You may have a bad fuel pump sock or you may have a plugged catilatic converter, does the truck take a long time to start after it stalls out?

maybe you need to have dianostics done on the inboard comp

its most likely the throttle body is dirty, just remove the air box on top of the engine and clean the throttle body out with carb cleaner.