Re: 95 Windstar engine cuts off at highway speeds.
Sounds like the Mass AirFlow Sensor (MAF) has bit the dust.
The Throttle Position Sensor and/or Idle Speed Controller (TPS & IAC) can both affect transmission shifting (commonly in and out of over drive). In some cases if you're careful the IAC can be cleaned with carb cleaner. It's just as easy to swap it out for a new one (about $40 for each sensor). I'm not positive but I believe the MAF can run close to $80 and it's generally located on the air intake tube going before the throttle body.
As the vehicle hasn't been running properly for 5K, you may want to consider a tune up with new plugs (gaped correctly) and wires.
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!