When I stop at a red light my RPM goes to about 500-550... So yours going below 1000 should not be to bad, but then again you have an older car so what would I know? lol

Anyway how many miles your car has? maybe you just need to adjust idealing rpm a little higher so your car is more stable...

Hows your car in N, and what about in D and just not pushing the gas, let it roll on its own, is that rough or only sitting still in drive?