2000 honda accord 3.0lt only reverse work

I'm sorry to hear about the issues you're experiencing with your Honda Accord. It seems like you've already rebuilt the transmission, but the car still won't move forward and has low RPM. Here are a few possibilities to consider:

1. Transmission fluid: Even though you mentioned that the fluid level is okay, it's essential to ensure that the fluid is clean and at the correct level. Dirty or insufficient transmission fluid can cause shifting problems and low RPM. Double-check the condition and level of the fluid to rule out any potential issues.
2. Torque converter: The torque converter is responsible for transferring power from the engine to the transmission. If it's faulty or not engaging properly, it can cause the symptoms you described. Make sure the torque converter is functioning correctly or consider having it inspected by a professional.
3. Shift linkage or solenoid: The shift linkage connects the gear shifter to the transmission. If there's a problem with the linkage, it can prevent the transmission from engaging the forward gears. Additionally, faulty shift solenoids can cause shifting issues. Inspecting and potentially replacing the shift linkage or solenoids might be necessary.
4. Internal transmission problems: Despite the transmission rebuild, there could still be internal issues that are preventing proper operation. It's possible that a component wasn't installed correctly, a part is damaged, or there's a malfunctioning valve body. In this case, it may be necessary to revisit the transmission rebuild or consult a professional mechanic to diagnose and address the problem.

Since this is a complex issue involving your vehicle's transmission, it's recommended to consult a qualified mechanic or a Honda dealership for a thorough inspection and diagnosis. They will have the expertise and tools necessary to pinpoint the exact cause of the problem and provide an appropriate solution.