Spark Plugs
 

Any one know why my trailing plugs smelt like fuel and were wet, and the leading ones had a lot of carbon build up?
Anyway I just changed them and the car feels a lot better now.

Your car is running rich.

I suggest changing your 02 sensor if you already haven't.

How old are the plugs?

And were they stock heat ranges?

The last time I changed them was about 10k miles. roughly 3 oil changes. Stock heat ranges. And i changed the 02 sensor about 4 months ago.
Thanks

Unfortunately this is very common due to Mazda's poor tuning of the stock ecu.
Buy a PFC and have it properly tuned and your plugs should stay clean along with your exhaust. But that depends on the tuner also.