What are the symptoms of a bad torque converter?

The two best performance enhancers (off engine) are gear and converter.
On an engine, the best performance enhancers are headers, cam and heads.
One the car body, front and rear suspension should be worked as a married pair. Front and rear.
Drags shocks at the rear and the front.
S/S springs at the rear, thin T-bars up front.
Rear sway bar and front sway bar.

Front and rear should be done at the same time. Then the effect is seen best.
If you can do the gears and converter installation at the same time, do so and the effect will be great.

Get one and put it to the side and wait for the other.