I had the same problem with my '88 300 sel. ABS would pulse after first brake application after initial start up and ocassionally when coming to a stop at low speeds. Both wheel sensors and differential sensor checked out as within spec. I remember reading somewhere that for some illogical reason the right front sensors seem to fail at a higher rate than the other two. So I replaced the right front sensor first. That was about 4 mos. ago, the problem has not returned.

brgds,

BENZSTER