After checking the next day, the timing was back to quite advanced, so think this is related to the electronic spark timing. Went through the process again and moved the timing to 4deg advanced and it does appear to run a bit smoother and the idle seems to be more consistent. Seems to have better vacuum as the brakes feel more solid. The idle does dip sometimes when slowing down to a stop but recovers more quickly and stays stable, but not as frequent as it used to be.
Interestingly, with the spark timing disconnected, i got no puffs of smoke when restarting and couldn't appear to smell unburnt fuel. As soon as i plugged in the EST, smoked came out and the fuel smell is back
I will have another long weekend next weekend, so i will pull the headers off, remove the AIR (even if it means cutting wire pipes and welding them shut) and then i can swap out the O2 sensor, see if that helps anything.
Also took the dizzy cap off and cleaned the terminals, looked pretty clean but ran some sand paper over to get rid of any corrosion.
Found a bit of a slow leak, appears to be coming from the lower radiator hose. Do have some replacement hoses, so thinking about doing a coolant flush over the winter and swapping them out, along with a new thermostat.
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