Is it difficult to replace the struts and shocks on a 2000 Chevy Malibu?
Shocks are easy to replace and any DIYer can accomplish that. However if you do not have the proper tools or skill, I suggest you pay a professional to replace the struts. Serious injury can occur when working with struts.
The 4Runner doesn't have struts; it has coil-over shocks in front. After removing the old shocks a spring compressor is required to remove the springs and install them on the new shocks. Take it to a front end shop that has the proper compressor and tools; it's very dangerous if you don't have good equipment and experience. The rear shocks are easy to replace by yourself.
If you have worn Struts on a vehicle, those can be replaced without replacing your springs. "Struts" and "Shocks" are often used interchangeably in language, however, I believe your vehicle is a front wheel drive with a double wishbone suspension. In this case, they would be more accurately referred to as "Struts". Just for reference. In either case, the answer is still, yes. Shocks/Struts can be replaced without replacing the springs as well.