2009 Honda ridgeline won’t go over 60 and dies when stopped

I have a 2009 Honda ridgeline with about 140,000 miles on it. I was driving to work this morning and as I was going to get on the highway and started to get over 60 my rpms would drop and my speed would fall and it felt like I didn’t have power. Then when I went to get off at the next exit I came to a stop at a stop sign and my truck died. I put it into park and started it again and tried to drive over to get out the middle of the road and it died as I was driving and wouldn’t let me move it anymore. I put it in neutral and pushed it to the median. I called my brother who’s a mechanic and he said try and turn my ac off and see what happens and then it started right up and I drove it the 5 minutes home not on the highway or over 40 but it drove fine all the way home. I put a cheap total pro alternator in it a few months ago because my original one went out but it has been driving fine up until today. Any suggestions on what it could be or what I should start looking at? Thanks