It could be that the Modulator is clogged. From your test it definitly seems that way. Normally when the ABS is at rest meaning you are not slipping, the ports should be opened and let the fluid flow through.

Cleaning the ABS could be very difficult task. It is a complex unit.

You can get a unit on ebay for around $100 or so, but the seller must guarentee that the unit is in working condition. I replaced mine and it works great now for two years. It eneded up not being the issue but I did not swap back. And it was not on a 93 accord but on 99 accord V6.