A904 problem

You checked the fluid level and made sure the kickdown lever was working? It is 90% the governor sticking; ohya, (might be a shift valve or combo of several) but if it's not at full idling in neutral and the kickdown isn't set exactly right; these things can lower the pressure and contribute to the governor sticking; since you said you move the lever around and it goes from first after that; cuz you are raising the pressure. Fluid level and kd setting by the book, then change fluid and filter. And drain the converter too if at all possible. TYPE F.