Idle problem

[azza11]

G'day guys, recently i have had this idle problem, my au wagon has a standard 4.0 with pacemaker extractors and a decent filter, platinum iridium plugs and in good health until now. It idles in traffic at 600 rpm, now it flutters up to a 1000 and back down again and surges while driving. Recently i've had done.

Full service
Coolant system flush
Auto service and flush including converter
Diff oil renewed
New belt
Throttle body clean
Upper engine carbon clean
Only other prob is cross firing leads, i am waiting to oder a set through QIS.

Car is driving a lot better, more responsive and better fuel economy despite the flutter its all good. Apparently the little step motors on the throttle body? are very good. Car also smells now due to coolant flush, its got a new block to thermostat gasket, new housing and new thermostat. Adding new rotors and pads all round, i have spent almost 1600 in 4 weeks. Dont know what else it can be, funny thing is it surges worse now that its had the above, apart from plugs what else is there to tune? Do i need a diagnostic of the fuel air done? I'd buy a flash tuner if required and get a dyno tune done but only planned this when i do the new intake piping and airbox mods i want to do. Any help greatly appreciated, i wanted to go to Willowbank in 2 weeks and have a crack at a 15 something.

AZZA