My Fairlane running like crap!!!!

[KR1STO]

Ok guys, i need a hand...

Yesterday, the car started running like crap, and backfired on gas..

Ok, my first thought were plugs and possibly coil pack..

so i did the cheapest..plugs..

put new plugs in today, checked the gap.. all 0.8mm

started it up and reset the ECU..

now, it still ran rough..

i took it for a drive and it wasn't idling right when i stopped..
both on gas and petrol..

anyway, as i came off the accelerator and back on it around a corner, there was a huge backfire on gas and then it stalled..

when i started it back up on petrol it was idling at 3000rpm...

sounds like its only running on 4 cylinders and wont idle on gas anymore..

my thoughts now... headgasket..

i took the radiator cap off and ran the car..

water was flying out at idle almost as if there was pressurised air running through it constantly..

Could the headgasket be split and pressurising the cooling system..?

Is this a headgasket prooblem guys or have i done a little bit more damage than that..?

the car is running really rough and idles at 2500-3000rpm..

i've checked for vacuum leaks but there doesn't seem to be any..


any help appreciated..

cheers
kris