I don't know if this will relate to your problem, but here are a couple of suggestions that I started with to pinpoint my problem:

1. Check to see if the vacuum line from the vacuum modulator [under the car and on the driver's side of the tranny (red or green)] up to the engine compartment is still in place

2. Unplug the vacuum line [the same one as in #1] to the tranny and see if it makes any impact [negative or positive]

3. Try manually shifting with the gear indicator

4. Try forcing the car to shift with hard acceleration and letting off the gas

By doing these, you might find a vacuum source for your problems rather than a tranny source

Don

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