vh 253 missing when starting at trafic lightsat

[vhbill]

engine miss firers when starting off car runs on lpg
THING I HAVE DONE changed all spark plugs this made car run ok for a short time. it was notice when spark plugs were changed number 6 cylinder plug was black, exchanged plugs in number 5 and 6 this made a run ok for a short time. replaced igition lead to number 6 cylinder no change in fault. removed plugs from cylinder 5 and 6 compression checked each cylinder reading 150psi. there is no blue smoke or oil useage what is wrong ????? help i am drowning

[BeNoS]

possibly check the dizzy cap and rotor make sure it isnt burnt out at all also if u have multimeter check the leads they would be the other things i would check first and also check ur timing make sure its within specs for the car running on gas timing is different to petrol running engines if i remember correctly

hope this helps