98 Windstar 3.8. Tranny won't shift to 2nd gear.

[snizzer]

257,00 miles, tranny was rebuilt around 90,000.
After warming up, tranny stays in 1st gear, won't shift to 2nd. While doing this speedometer quits working too. What I have done to get it to shift is shift to second gear manually, it does shift when doing this, then I shift back to drive, and it goes into 3rd gear. This only does this intermittently after warming up. Sometimes it shifts normally, then goes into this non shifting thing, and then the speedo quits while it is doing this.
Another weird thing this van does is, while driving with foot on the throttle, but not accelorating , the car bucks back and forth, until adding more gas.
Any help appreciated, Thanks.

[wiswind]

There are a lot of things that can cause this......
1 thing that jumps out is the lack of speedometer when the problem happens.
Do you have the mechanical speedometer (needle that physically moves) or electronic?
If mechanical.....there is something wrong with the physical drive for the speedometer cable......on the end of the vehicle speed sensor......which has a mechanical connection for the speedometer cable AND a electronic connection for the PCM.
For the electronic speedometer......we are still looking at the vehicle speed sensor.

If the vehicle speed sensor is not working......the PCM does not know how fast the vehicle is moving.......so it does not know how to shift the transmission.

The Vehicle Speed sensor is mounted on the back side of the transmission.....roughly the middle point on the motor/tranny assembly.....right above one of the catalytic converters.

Another thing that can cause problems with shifting (that is not inside the transmission) is the Transmission Range Sensor......also known as Neutral Safety Switch.
This can go bad in 1 or more positions........
The TRS tells the PCM what gear you have selected with the gear select lever in the vehicle.
There are LOTS of connections inside that small box.
The TRS sits on top of the transmission......the cable from the gear select lever connects to it.