This is EASY! When your liftgate wont stay open, you can replace the liftgate strut. I show the simple instructions on how to make this replacement, removing the old and inserting the new strut. Many cars only require that the right strut be replaced. Some older model cars and not automatic lift, will need both struts replaced. Not to worry, the Amazon link below will take you to the right spot to search for the correct part by your car model.

Here is the link to the strut replacement for my 2013 Equinox. https://amzn.to/3xNicEg
If you need to search for other models than Chevy, click on the link above, then just insert the model and year of make in front of "Liftgate replacement Strut" in the Amazon search box.

Strut replacement can be done in 5-10 min.