I had a similar problem with my 2000 GTP, "ABS" light would illuminate after the engine bay warmed up, but if I kept my trip short enough and didnt allow the car to warm up between usage, the light would not re-appear. A trip to AZ and a free code read of the ABS controlled showed no codes, but my ancient OBD II software (car-code) that I have on an old laptop has enhanced data read would show me a "1571" code once and a while, and the "requested torque" signal from the ABS controller would freeze at 100%, triggering the ABS light and loss of MAGNASTEER (steering got hard at low speed). I pulled the entire wire harness from the engine bay and opened it up and found a chaffed wire held on by only one single strand of copper wire, but it went to the transmission and was not yet causing any driveability faults.
I ended up sending the ABS module to "MODULE MASTERS" for rebuild, problem solved!
