[Alan Roehrich]

Do not just replace parts arbitrarily. It has not worked so far, and is not likely to work, at least until you have spent way too much money.

The next thing to do is to perform the appropriate pressure tests on the transmission.

It is the pump that charges the converter with fluid. The valvebody controls line pressure, and as a function of line pressure, there is charge pressure to fill the torque converter with fluid. It is possible that there is one or more problem inside the pump.