You have an Aisin Warner AW4 transmission. Of course a tranny shop is going to insist you need a rebuild. Don't. First, your problem is likely not the tranny itself. Second the AW4 doesn't take well to rebuilds, even by a good tranny shop. Third, $2300 is a serious rip off.
The TV cable on the AW4 does not affect the shift points, just the shift firmness. It's easy to adjust and you should probably do it anyway. The shift points are decided by transmission computer, based on the throttle position (TPS sensor) and the shaft speed sensors on the tranny itself.
If it is not shifting correctly, more than likely, you simply have a bad TPS sensor. This is a very common problem as it is a mechanical sensor which can wear out or get damaged if water gets inside. It's located on the side of the throttle body and very easy to change. Figure about 10 minutes to change and $30-50 for the sensor depending on model year and where you buy it. I would try replacing that before going back to the questionable transmission shop.
As for the engine losing power, I start with a basic tune-up with new plugs, plug wires, cap and rotor. Especially if they've never been done. I would also consider replacing the front O2 sensor if it's still the original and you're getting poor mileage. Should be under $100 for parts.