Just checking to see what the general consensus is as to what could be causing my problem. Only occasionally, My 00' DII will idle rough. Around the RPM range of 635-660 or so when in gear.

 

Oh, the usual; plugs, wires, coils, sensors of choice (TPS, IACV), coolant leak (head gasket), vac hose leak somewhere (cracked or split). MAF needs cleaning, etc. Maybe look under the hood when it is pitch black dark and see if you can see any arc over from ignition related parts.