Rep Power: 0

Hello,
My electrical flipped its **** on a drive today. I'm hoping someone has a good idea about where I should start looking first., I have no experience working on a vehicle this new, so I dont know where to begin.

It was reasonably but not crazy warm out, and I had the AC on.
Drove about 70 miles today, first 40 were in traffic. About 15 minutes after I got up to 70 and was cruising. Then all of a sudden the digital speedometer started jumping from 70 to 0 to 25 for a split second, then up to like 42, then back up to 65, it would hold for a couple of seconds, then drop back down to zero. Pretty quick after I pulled over to see if there was any smoke coming out of the car, if the tires or hood were unreasonably hot, or if there was anything hanging off the car. No dice. A few months back my rear passenger window stopped rolling up or down and so I figured it might be related. Historically I have had no other electrical issues except for very occasionally the fans will lose a lot of power and just sort of dribble out heat or AC. Anyway, the car fired right back up no problem, so I kept driving. Pulled up a sound file on my phone that was just one single sustained note to see if the stereo was acting funny, and sure enough, the volume would jump up really loud for a few seconds right before or right after the speedometer would read accurately, then dip back down to a muffled maybe 1/3 volume when the speedometer read 0. These two effects tended to oscillate together but not every time. Possibly notably, I turned the AC off but when i would turn it back on periodically to check if it was losing power, that didnt appear to be the case. Now im freaking out but im a few miles from a friends house. I keep driving. About a half mile before I get there, "Check power steering" pops up on the dash for about two seconds, then disappears. I get there, park, pop the hood. Same story. No excessive heat, no smoke, no burning smells. I leave it for a few hours, then head home. Same original two issues are happening, but i have noticed that the odometer isnt updating, and the power gauge stays at 0 mpg while the speedometer is 0. So now im holding onto hope its just the VSS and the power loss issues are just the car thinking it cant draw too much power. Anyway, I'm driving, doing about 60 to 70 the whole way home. Its considerably cooler out now. About 5 miles from my house the "check emissions system" message pops up, then shortly after the "check power steering" pops up again, and stays on. I didnt notice any loss of power steering but i pull over, turn the car off, check everything again, nothing out of the ordinary. No smells, nothing. Car fires right back up, check emissions message stays on but the power steering message is no longer up. The speedometer, odometer, and stereo issues persisted as well.

I didnt notice a significant loss of horsepower. Maybe a little bit, but the clutch is getting up there in miles and I cant be sure if its a confirmation bias either way. But I can say with certainty that there wasnt a drastic loss, and if there was, it wasnt happening alongside the other stuff.

Im gonna take it to a mechanic tomorrow unless its something that is obvious to one of you that I should try first. If it isnt obvious but its a limited number of things, some guesses or suggestions would be helpful before the mechanic sells me on 2 grand in diagnostics and whatnot.

 
Rep Power: 222

Alternator may be on the way out. Maybe bad battery connections