2002 Trailblazer stalling when driving

Lots of possible problems. Look here for Trailblazer issues.

http://forums.trailvoy.com/showthread.php?t=72999#/topics/72999?page=1

I would think maybe the crankshaft sensor but you have no DTC's.So i would check the fuel pressure it could be a weak pump.

The throttle body needs to be cleaned, grime in this area prevents the throttle plate from closing completely and allowing air to enter, making the air/fuel mixture lean

you might want to look at your O2 sensors, they can cause the motor to run lean or rich. also you might have an electrical issue that is tripping your ECM. your electronic control module might be faulty. best solution is to get a trouble code reader and find out what your on board computer has stored. from there you can repair and clear the codes.

Is she getting any check engine codes?

If not, perhaps during a repair attempt someone knocked a vacuum line loose or even just pinched a hole in one.

Her engines idle air control probably can't deal with the vacuum leak which would explain the irratic idle and final stalling.

A vacuum test would confirm or rule this possiblity out. So would spraying a little WD-40 or even a little water on the vacuum lines and check to see if the idle smooths out. You just have to go slow so you can be sure where the idle picks up versus where your spraying.

A mechanic with an OBD 2 scanner could pllug in and watch what all the sensors are doing in real time to see whats changing and how the engine is trying to compensate.

Good luck and be careful,

check fuel pump pressure or clogged fuel filter

check the idle sensor and map sensor

check throttlr sensor

Your are correct. The ignition switch has tumblers inside and are not releasing . You need to take the vehicle in to have the igniton switch replaced. Then you should be okay .

Sounds like your coil is going out. when they get hot they will go out and when they cool back down they will work normally again. If you replace the coil you will be good to go. Thanks for using FixYa and good luck!