Codes P0303, P0306, P0305 and P0300, battery drain, cylinder misfire and running lean

Hello, I just bought the car listed above and have had a few problems with it. It’s throwing p0174 and p0171. I just changed sparkplugs and now it’s throwing codes for cylinders 3, 5, and 6 misfire p0303, p0306, p0305 and p0300. While checking for anything that would obviously cause this, I found that after about 45-50 minutes of the engine running all lights on the dash came on except the battery light and after I cut the car off and tried to cut it back on there was no power. I charged the battery, and it did the same thing. It will run and drive fined up to 3,000 RPMs when it starts sputtering until you cut the car off and cut it back on and it returns to normal.