My car has been drinking petrol like it paid for it the bastard.
From what I've searched I need to check/change the following:

Injectors.
Would I need to change it or just clean it up?
If so what would you guys reccomend for a DC2-R

Fuel Filter.
No ideas about these, what should I replace em with?

Spark Plugs.
I was thinking replacing them with NGK Spark plugs?
(Any Other reccomendations/review on these welcome)
And would I have to change the spark leads as well?

Thermostat.
Was thinking of replacing these with Spoon B-series Low Temp Thermostat
What do you guys think?

O2 Sensor.
I was also thinking of replacing this with NGK's O2 Sensor?

Upon replacing all of these, my DC2-R should be drinking less petrol/making more mileage correct? Im so unsure.
If there is anything else I've missed that may affect Fuel consumption please do add.