If your son observed that the Engine Stall happened when making a Left Turn... There is a unique problem with the Trallblazer LL8 4.2L Engine dying due to the fact that THREE DIFFERENT MODULES share a Common Ground and all three can conspire to cause the Engine to DIE if THESE Engine Block Grounds are either Broken, Loose or suffer from Galvanic Corrosion. Be advised that
The Left Head Lamp, The Left Turn Signal ...AND... The Fuel Pump Relay located in the Fuse Box under the hood ALL Share the
G-107 Engine Block Ground as shown below:

IF the Grounds on the Left (Driver's) Side of the Engine Block are compromised... whenever making a Left Turn with the
Left Turn Signal engaged...the
Left Headlamp will begin to flutter and the
Fuel Pump Relay will
DROP OUT due to an excessive amperage draw by all three modules occurring simultaneously and the
FUEL PUMP WILL DIE AND CAUSE AN IMMEDIATE ENGINE STALL.
As per a prior suggestion made by
@movietvet ...If this becomes proven by a physical inspection... the Solution is to
Remove These Grounds from the Engine Block, . Clean all surfaces down to Bare Metal..., then Apply a Dollop of Dielectric Grease in between all the contact surfaces and Snug the Grounds back up against the Engine Block as shown in the encircled highlights in the photo just above.
Also... Recently... Thanks to the suggestions made by
@TJBaker57 to another Member on a different Truck Platform that the problem might be evolving with
Open Circuit Copper Wire Traces hidden and sandwiched in between the design of the Fuse Box...
...That Member investigated and found
BROKEN COPPER WIRE TRACES in dwelling and was able to *Re-Wire* those in place with 20 GA Solid Copper Wire and this fixed his issue. These Videos show precisely how this action is performed: