very rich smell on start up

[damo66]

i have noticed it has started to smell very rich on startup and possibly when warm, just less so...
I am currently doing an mpg test (brim it, use it, brim it then calc) to see if it using more than it should.
Cleaned the MAF a couple of weeks ago.

Any hints or tips as to why its running rich?

[Carolyn]

How's the air filter? 

[damo66]

had it out the other day and it looked nice and clean