it only seems to be missing on 1 cylinder, the gas system is solenoid operated so will only start on petrol then it automatically switches to gas after a few seconds, i can switch it manually to run on petrol but doin so it obviously misfires, the timing and evrything has been set up correctly by my dad but we didnt think to check the injectors. im ust hoping its now down to a lose/dirty connection on 1 of the plugs, checed them all drver side but no diference so hoping its goin to be under the inlet manifold will check later on in the week when i have more time