RPMs

I have a 2012 Nissan Rogue and off and on for almost 2 yrs it would suddenly stop getting power when I was driving out of nowhere even with pedal all the way to the floor, I never found 2 and 2 but I learned that resetting my battery fixed the problem so that's what I did when it would do this out of nowhere and never throwing a code. I went out and started my car the other day all was fine it started throwing a code at me and it was really rough driving. Took it easy got it home put it on code reader and said something about torque converter but stopped acting funny code never popped again. Few days later I go to go somewhere car starts as usual gets Rpms smoothly I put it in reverse no go go.... I put it in drive no go go... It wasn't gaining rpms on tachometer nor was engine gaining power even with pedal on floor, which is very similar to what it started doing almost 2 yrs ago except I'd already be on the highway going somewhere not have it not gain power from the time I start it. I read on one page it could be an alternator being bad, but I don't see an alternator taking 2 yrs to come to this problem. A sensor in the throttle somewhere possible but torque converter since that code was only thrown once I don't think would be the culprit. Just in my process of elimination but if I'm wrong I'll own up to it. I just hope it's something I can fix cheap and easy because I can't work due to PTSD and we are trying to get income going on it but the government takes its time and we only have my husbands's income who is 20yr vet in national guard and is getting out because of my mental health so we are losing more income because of me. I can usually fix most things myself having been around a dealership and my dad being service manager as long as i can recall growing up. But the computers have changed everything since he left that work, and sadly he's not speaking to me over a petty misunderstanding that I can't make him understand and I hate not being able to go to him over this.