If I recall correctly, the idle was essentially stable, just very rough. The revs weren't fluctuating widely.
The idle problem was addressed first, and then the oil was changed. I don't think the idle speed regulator was much of a factor in the low oil pressure observed. The pressure was high- normal when cold but as the engine warmed up, it trended down even at normal cruising speed. At idle it was around the "1" mark.
You might want to have the oil pressure checked with an external guage to verify the observed readings.