2000 Accord 4cyl Auto Transmission Slipping

I bought a 2000 Honda Accord SE with 122000 miles. When starting from a stop it will free rev until you let off the gas and apply the gas the second time then it will start to go. It also seems to not want to go into second without revving up around 4000 RPM. When slowing down for a turn, it will free rev when going from the brake pedal back to the gas, then have to let off the gas and reapply again for it to fully shift.

Does this sound like the transmission as a whole is bad, or the torque converter? Would a fluid change or flush and filter help anything? I just got the car to go around 25 miles a day to work and back for the next few months. Someone I know thinks there’s a sensor that could be changed that’s causing the issue, but I know these transmissions are notorious for failing so I was doubting that.