HELP!! 2004 aveo losing power going uphill

I just bought an 04 aveo 5 speed manual yesterday. I know next to nothing about cars so please bear with me. The check engine light is on. I went to have the codes checked today, I don't remember the exact codes but there were 5 of them. 3 were the same for crank Something. And the other 2 were evaporative emissions something small leak. I read about the gas cap being able to turn that light on if it's not tight enough which it wasn't and it's broken so I can contribute that to that and get a new one Anywho today I drove about 2 hours from where I live, highway speed limit 65 with lots of hills. The car accelerates just fine, engine is quiet and I get lots of speed and power, on flat roads. Start to go up the hill and begin losing speed, rpms go down steadily with the speed so I end up going 20 on a 65 mph highway and "flooring it" going nowhere. It feels like the car is cutting out like it's just going to shut off but it's mild and the car doesn't die. . once I get up the hill the car picks up speed again and drives like normal. Please help I love this car already haha any help would be greatly appreciated. I also have a mechanic fixing the crank whatever it is tomorrow and it's only a 50 dollar part if that helps anyone. Thanks

I'm assuming this was bought from an individual, otherwise you would have gone back to the used car dealer, correct? Caveat emptor.

We could speculate on what's wrong, and come up with probably 20 or so possible reasons for your problems. However, since you are working with a mechanic right now, you should just continue along that path until it's either been fixed, or you lose confidence in the guy. Be advised that probably the worst thing you ccould do would be to give your mechanic advice based on what anyone on this forum (or anyone else for that matter) has to say.
Hopefully he'll fix it and you will be all set. If not, you can post back again with an updated history.

Yeah I bought it from a dealer as is. It's one of their trade ins so they supposedly wouldnt know what was wrong with it, if anything. So it was the cam shaft sensor. He replaced it and I bought a new gas cap. But now as soon as I got in the car I could tell a difference in it idling. It vibrates roughly as if it wants to die but it doesn't. Shifting still seems normal but while accelerating it vibrates and spudders, feels like cutting out all the time. So I took it to auto zone to have the code checked on my now flashing check engine light and now all it comes up with are 2 codes for a misfire? The mechanic mentioned that it could be the spark plugs and wires. Could all my issues be related to the spark plugs? I'm not sure about my mechanic now, but I'm the one who knows nothing about cars so he could be right. Can't afford to spend extra money on a second opinion from a mechanic for just diagnosing so I thought I would come back here.

You're not clear about exactly what this mechanic has done. If the guy diagnosed it for any length of time, and then said it "could be the spark plugs and wires", that doesn't sound good to me. He should be able to pull a plug and wire and say yes or no about replacing them based on their condition. "Could be" doesn't cut it for a pro. But OTOH, if he just said that without diagnosing, then sure, it could be the plugs and wires. The problem is that it could also be a bunch of other things as well, and paying shop rates for part hanging gets real expensive real fast.

The good folks here could suggest a number of possible reasons for a misfire, but it's all speculation without hands-on diagnosis of the vehicle. Given that you don't DIY, IMO you need to find a good mechanic who will do a full diagnosis of the problem and give you an estimate of the repair. With an unknown history, and an "as is" sale, you really need to know if your new Aveo has big $$ problems before throwing any more at it, beyond the diagnosis charge.

I haven't ever had idle issues, but i have had to replace my coil pack twice because of a misfire on acceleration. First time my original went bad so i was cheap and got a used one a junk yard which lasted about 2 years. About a month ago i got the same syptoms and replaced the used one with a new one. both times my coil pack had been the issue, not saying this is your problem but maybe look into it, pretty easy to replace too. Keep us updated.