Last week I was taking my 986 to the dragon

[papasmurf]

and got about 2 hours away and the brakes suddenly went soft on the highway. I pulled over and got off the highway and drove about another 2 miles where it happened again with the brakes going soft and pedal going mostly to the floor. Each time this seemed to happen for about 1-2 seconds where upon pedal pressure came back. I limped the car around at low speeds but there were several times where the steering would jerk slightly as if the driver side front brake was locking and releasing along with a popping sound as it happened. The sound was apparent when leaving a complete stop too as if the brakes had frozen slightly similar to how your brakes rust over after a car wash. Shortly before this happened while sitting on a slight incline in traffic I got the impression that the brakes were dragging as I figured I should have been rolling based on the angle of the road when the brakes were released or at least rolling more than I was as it seemed the car was slowing more than it should without brake assist. Of course this killed my trip to the dragon and I wound up having to ship the car back to Texas. I got a hotel and jacked up each corner of the car and the fronts were definitely dragging. The rears from what I could tell were fine though at the moment I had the parking brake engaged so it didn't tell me too much. I pulled the ABS fuse just to see if the condition would improve and if the car could be limped home but within miles it was obvious the problem was coming back and I am pretty sure it was getting worse the increased heat of the brakes dragging. The car is now home and I scanned the ECU with my durametric today and got code 0501. I was thinking maybe this code popped up because of the fuse being pulled so I cleared the code and pulled the fuse but it did not trigger a check engine light apart from the ABS/TC lights. I drove the car about a mile just to see if I would get a CEL again. From the research I did, 0501 is the left rear speed/abs sensor? Would this impact the front brakes? FWIW I did just replace the rear axles before the trip but the car drove about 12 hours at least before having any issues? Is there some specific tests I can do with the durametric to get to the root of the probem?