Hey guys, my Ef Ghia has a bit of an idling / misfiring issue which i hoped a basic service would fix but didn't.

Basically at idle it will start misfiring and stay sitting at around 550-650ish rpm, sometimes it will idle perfectly at 750ish rpm flat and have no problems.

Dont think itd be headgasket as theres no change in the oil.

Car used to occasionally idle like this when it was low on fuel or when the battery had been left off for a while but would always fix itself fairly quick.

Service was -
plugs
leads
oil
oil filter
coolant
thermostat
have fuel filter here to do aswell

Dont mind spending the $ to get it running right, just not sure what to do at the moment.

I have a wrecked EL Futura here i can swap parts with to diagnose the problem

Just want this car to run perfect again as im lending it to a family friend who needs it for work, so basically i need it as reliable as possible.

Cleaned the intake and isc lately?

Good idea, i used to have to clean the ISC out fairly often but havent done it in a while.

Keep the ideas rolling i only have access to the car twice a week atm so if i can get a list of things to check i can go through them point by point when i have the car here.

check over intake manifold. Spray around bolts with water see if that fixes it. If so just nip up some of the intake bolts.

Also oxy sensor? fowled maybe
harmonic balancer seal?
engine mount broken?

Has your balancer moved? Coil pack? Bad fuel? Fuel filter? blocked or fowled injector?

Unplug the isc completely and see if it fixes it, if the revs drop right off and it dies you could bump it up with the idle screw, ive done it to mine as i put new isc in and it didnt fix it just rev hanged and carried on when it felt like it so i dont run the isc at all and it humms on LPG and petrol. The isc's are prone to issues. Also check your PCV it could be blocked, start with the easy things 1st as usually idle issues are simple to solve.