TB42 running on 4 cylinders?

[Parksy]

Bit of an update.. Ran 12v straight from the battery to the coil and bypassed the resistor and then checked all the leads/plugs were firing. Found that while on 12v cyl 2 was firing, however when removing the lead the change in engine rpm isnt quite as noticeable as 3/4/5/6. It ONLY did this on petrol. So I'm just taking a guess here but, leaking intake manifold somewhere around 1+2? Because gas is more pressurized than petrol it would be able to leak out easier, meaning that the cyls would still be getting fuel, just no where near as much?

Replace the intake gasket, use some spray on sealant just to be sure. Might be a pain for a few hours(by doing it I mean) but then it might solve your issue and if not, it's one thing eliminated. Gasket replacement is a cheap fix if you do it yourself.