Help with rough idle

[1976450SEL]

I have a 450 SEL 1976 and am having poor idle and starting. the OVP and the idle control valve sound like the culprits to me. Where are these on my car?

Any other ideas?

The car starts poorly (need to push the gas to get going) and then either idles high at 1200 rpm or low at 500. Doesnt seem to be any rhyme or reason.

Thanks for any help and on helping me locate on my car.