Can't get idle right on '79 280zx

[TheBettie]

I have a '79 280ZX and have just replaced the catalytic converter which was clogged and the exhaust going from the manifold to the EGR was melting the hose that the previous owner had spliced the EGR tube with. Now my idle's WAY off and I can't seem to adjust it. A friend and I replaced the head, manifold, all gaskets, hoses, air, fuel and oil filters. When we were timing it, his timing light broke so we timed it by ear and it ran fine for about two months until this. It sounds as if the idle's too low and even though the distributor is advanced past where it should be, I can't speed it up. HELP!