Deffo sort all the earths out first - that dodgy knock sensor connector isn't brilliant either, neither is the hose to the fuel pressure regulator. New HT leads and a dizzy cap and rotor arm wouldn't be money wasted either.
Then see what you get at the battery from the alternator, and how it runs then.
If the voltage is okay and it's still miss-firing a bit on light throttle I'd look at the lambda. Did you find out from the previous owner what wiring problem he'd had there, and how he fixed it?
I think the 'jumpyness' pulling away is partly down to a dewedged throttle body, made worse by the miss-fire you've got - so you'll never completely irradicate that unless you stick the wedges back in. Problem is, that the MAP sensor value swings around a fair bit for next to no throttle input - which makes it very difficult to map in that area. With the wedges back in the MAP value is more progressive/stable at low throttle openings.
