Oil Problem?--94 Buick Regal

today while sitting in traffic--my car's oil light didn't come on, but looking at the pressure sign it was staying in between 0 and 40. And when I was completely stopped, it would stay at 40.

Now I just got my oil changed, but it seemed to sputter. So instead of my car dying out, I put it into neutral. But when I finally drove at a good speed, it was hard to get some acceleration.

Was my car like this because its so old and standing still for so long? Help?