What happens when you put back in the old relay? I had the ABS light coming on occasionally, coupled with a low idle in my 89 300TE. After replacing the OVP relay the problems stopped. It makes me wonder if you got a bad relay.
I wouldn't rule out worn brushes/bad regulator either.

__________________
Fourings

84 Audi Coupe GT with Turbo engine, EFI (buh-bye CIS), Jamex seats, Koni's/H&R's, e-code lights. 210k and counting.
1992 Anthracite 400E, 161k, "Grey Ghost".
1986 VW Quantum Syncro, 192k, gone to the crusher in the sky.
1989 300TE 172k. (Was mine, now also Mom's car)
72 280SE 4.5 (Mom's car)