One way to troubleshoot a 700R4 is to check the governor, which stops the transmission to upshift. Made of nylon and plastic, the governor may break off from wear. Most transmission shops carry replacement governors.
Another troubleshooting action is to check the 3-4 clutch pack, especially if there is the loss of the second, fourth or reverse gears. The 3-4 clutch pack may also break, and if it does, it is probably due to a throttle-pressure cable that is not adjusted correctly. It is also possible that the 700R4 has band servos that are failing, but it is usually due to dirty or low transmission fluid.
If the 700R4 has line pressure that is not adequate, the troubleshooting step it to adjust the TV cable. This can also cause the third and fourth gears to fail quickly. This is not an issue with age, as this could occur in a transmission that is new or one that has more than 100,000 miles.
If the overdrive gear does not function in the 700R4, it is usually the fault of the input spring. In this case, the transmission may not shift into overdrive, but it shifts from first to second to third gears. This is a repair that a professional must do, so get the car to a transmission shop slowly and carefully.