Same on mine that was dragging. New hoses moments after it arrived in my possession.
Car is in hibernation now, when it is out again I will try to get them to bind up and try the vacuum hose removal. It will almost certainly not be the problem as once while driving on the freeway they were binding up to the point of full throttle, including boost, to maintain 90 km/h. I stopped for fifteen minutes, when the vacuum would have been atmosphere, and they were still tight after ten minutes. After the fifteen they were less tight though driveable, I just did not use the brakes for a few minutes (freeway, achievable) and they freed up a little. Eventually they went back to normal and the drive home (that day) was fine.
Breakdown:
1990 model
New OEM/Brembo rotors
New Brembo pads (would not recommend, always sqealing)
New brake hoses (good quality, forget brand)
New fluid
second hand master cylinder from a 940
Turbo engine completely stock
ABS, again untouched.
That leaves the booster and the ABS unit not replaced. I recall from tech when ABS was new that the ABS system on the car (which was current back then) had three systems. Two front and a rear. All it did was open a valve to release pressure when a wheel speed sensor was moving slower than its two peers - i.e. locking up or locked up. Not sure how all three of these valves could be binding up and causing all 4 wheels to bind up. I believe the new ones have pumps in them and can also apply the brakes if needed, the old ones are quite simple and can only relieve pressure.
Oddly, the front right wheel will 'un brake' via the ABS at very low speeds too. Talking driveway speed, walking pace. Cleaned up the sensor, no change, and have a spare ABS unit for it. Wiil get to that after a few other projeccts are finished.