2002 Chevrolet Trailblazer jerky on bumpy roads

Shock absorbers are the last thing to suspect. Have the vehicle inspected at a tire and alignment shop. They specialize in finding the causes of handling problems and noises. The smaller Blazers have a real big problem with repeat failure of the upper ball joints. I have not seen one separate yet leading to loss of control or crashes, but it is real common for them to make clunking noises and to allow a wheel to shift position while driving. Shifting position changes the alignment which can result in intermittent pulling to one side, shifting steering wheel position, and darting slightly from side to side.

A lot of manufacturers have been having trouble with worn control arm bushings too for about the last dozen or so years. That will also allow a wheel to shift its position. Anything that allows a wheel to shift will cause a variety of handling problems. Shock absorbers aren't involved in that. They just reduce a wheel's tendency to keep bouncing after it hits a bump.

You have to go by your mechanic's observations and recommendations. I'm a specialist in suspension and alignment, but I have to be able to see movement when I poke and pry on parts to tell if they're worn or a safety issue. Over a computer I can only go by what you describe and the corresponding typical solutions. Based on my past experience with upper ball joints on Blazers, at the mileage you listed, and the vehicle's age, they should have been replaced multiple times already. It was necessary to replace them on two former coworkers' Blazers every two years, but I think mileage is a better predictor than age.