I'll preface this by stating I'm no expert. I've only done Two of my own and many 727's for my racecars.
If it's intermittent, there are many possiblities including the VB but I'd start by dropping the pan and adjust the intermediate and reverse bands, install a new governor solenoid, pressure transducer and output speed sensor.
Inspecting the pan for clutch material will also give you an idea of the condition of the clutch packs.
When the front band is tightened during the adjustment, take note of the thread protrusion above the locknut. If it's flush or below the locknut, the band is worn. This just gives you an idea of the condition of the front band It does not necessarily mean the trans is ready to fail but at 145K, it's certainly possible. This should cost around 125.00 or so and easy to do. At 145K, If the pan has lots of clutch and band debris, I'd seriously consider a rebuild.
Good luck!