i recently revived my mums old ED falcon, it was over heating and the revvs were all over the place under any condition. like cruising at 80kmh and the revvs would come right up and the car would speed away. mum parked the car out back and bought a BA fairlane g220. 6 months later i deside to fix it and find the top tank on the radiator was F**k'd so i put a brand new radiator in it and then while letting it idle and self bleed the cooling system after about 5 mins it cut out. so i started it again and it died after 1 min then wouldnt start, knew it would be a fuel pump kicked the fuel tank and it fired up and ran for 10 mins before stalling again. fitted a new bosch fuel pump and she was all good. sisters bf drove it for a month, put a battery in it and then it sat for another 3 months. i jump started it a few times to move it and again about 3 months ago to use it as my daily but it wouldnt idle. i cleaned out the throttle body and the idle air control thing on the throttle body, still wouldnt idle so i screwed in the butterfly stop screw a s**t load til it would idle. it idles poorly when cold and if you lightly depress the gas pedal it stalls (cold only) but every now and then the idle spikes up and down, like ~800rpm too about ~1700 for about 2 - 3secs then back to ~800. all im wondering is if the solenoid on the idle air thing is stuff or needs resetting or if anyone else has had this or similar problem. ive sprayed start ya bastard around the intake manifold gasket checking if the revs spike for an air leak but nothing.
p.s sorry bout the cars life story but might help someones mental diagnostic skills

im 98% sure its not a headgasket either.

I had the same problem with my eb bad idle and what not. What i done was clean the isc out with petrol and make sure you take the solinoid off it to clean it. Clean both in petrol new gasket and o ring for the solinoid then clean the connection on the map sensor and check vac lines. Mine came good but try it if not you might need new isc or map they usually cause bad idle. good luck

cheers bud will do, that was my next step to check/replace the map and check/replace the solenoid on the isc. might just replace all vacuum lines anyways considering the age of them

Good luck mate thats what i done.