Help Please

[tiersum]

Hey all bit of a problem my car is just using so much fuel 96 vs commodore v6 auto 78,000km im getting about 280 out of 50L on 95 i find that is quite high normally it gets 380 ive noticed a slight miss which is intermitant would a missing engine cause a high increase in fuel use , i has platnium plugs leads were replaced at 60,000 im guessing it could be a coil or the dfi not much else it could be there are no errors , i need to try and figure this one out my self as i am now unemployed company i was working for has gone bankrupt so i need some help boys and girls please cheers last thing i need now is my pride and joy costing a fortune to run

[tiersum]

how can you test if you have a faulty coil or dfi modual