FIGHT FIGHT FIGHT FIGHT FIGHT!!!

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I gave this some thought today. sounds like your coil is getting too much voltage. If it gets worse the longer it runs, it must be getting hot. If the lights being on cures it, then I would say either there is something wrong at the ballast or the voltage reg is causing the alternator to hike the volts too high. When the lights are on the voltage drops and the coil behaves normally .
Check the alt , reg , and ballast.

thanks il give those things a go i guess its just trouble shooting till i find it.Its not just the lights either the thermo fan cutting in also reduces the miss.Its like the more load on the alternater the better it gets.Mite b a job for a professional. Thanx 4 ur help mate

Check your current draw across your various fuses. Feel for heat on any of them. Especially the one in the headlights circuit.

Then check your battery/alternator circuit.
Should be over 12V with engine off. And 14.4 (STEADY) when the engine is running. Test this when the headlights are on and when they are off,it should still be 14.4V (This tests the regulator).

Sounds like an excessive current draw somewhere in the system. Does your coil get REALLY hot? So much that you can't touch it?
It could be the coil is dying.

I agree that the symptoms are VERY strange. Maybe the headlight relay is shorting out when the lights are turned off? Hard to tell.

I hope this gives you something to think about.

My 1200 ute has a big miss on idle and it gets worse the longer the car is running the weird thing is it stops when i turn the lights on!! i cant figure it out any help would be great. The motor is an A15.