Battery issue!!!

[itsxthexslim]

Hello. New to forum and could use some help. I have a 03 H2 that I purchased in 2007 with 49k miles currently in 2015 truck has 77Kmiles. I have been having a battery issue since the beginning and now im thinking it has nothing to do with what I assumed. I rarely used truck it was the family and car show vehicle and towing my motorcycles to shows. I put stereo, rims, lighting, etc. I took battery that came with truck out and installed a kinetic battery. I thought battery was dying because it couldn't handle the stereo. So installed kinetic and that didn't last long at all probably one summer if I recall. Again I didn't use truck during week a lot. So I did optima, same issue. So I decided to have everything checked and found no problems. So I got out of truck show scene, sold rims, downgraded stereo a lil bit not much. I had tune up, water pump and a interstate battery installed. Ocassionally truck was used and I actually had father drive truck around so it just wouldn't sit so much. Battery dies again after not using it for a little while. so I go to jump it and notice terminal is loose. So im like oh that's good don't need another battery. thank god. Change battery again to a GM AC delco battery and do two band new terminals because other ones were rusty. Cool. literally 2 days later my father calls me hey your truck wont start. WHAT???? So he jumps it. Truck is idling like it wants to die then rpm goes back to normal then same thing idle drops just keeps fluctuating up and down. We drive it for a lil bit and notice fluctuating is still there but not as bad. Im lost now on what issue is. Everything is testing fine. today I googled bttery issue and saw the onstar was a issue. SO I took fuse out. I will see tomorrow if it starts btw I did jump it today and let it run for a bit to charge battery. If anyone has any info or ran into problems please feel free to help out. Any and evry issue you have found and how you fixed it would be great thank you.
I didn't mention this before but I am on my 3rd radio. I took out the bose, installed a alpine touch screen, and now im on a pioneer touchscreen. So I eliminated radio issue. I also previously had cluster checked because the lights wouldn't turn on when headlights were turned on so I guess I eliminated that.