EGR Valve... how effective is...
 

... cleaning it with carb cleaner? I soaked and swabbed it pretty hard but my dad is telling me to just change it.

Is cleaning it pretty effective or should I just change it?

Change it. Fortunately it's not that expensive of a part. Cleaning it up might get a day or two out of it but why address the same problem twice when you don't have to.

It really depends on the issue with it. If the diaphragm is bad then all the cleaning in the world won't help (it actually could make it worse). If it is just stuck open do to carbon build-up then a good cleaning can bring it back for a long time. The good news is they are usually very easy to get to on the GM trucks so if you do have to do it twice it isn't a huge waist of time.