A1EK

Hi Guys.

When I drive my car first thing in the morning, it runs a little sluggish and hesitant at slow speeds, but after 30 secs or so the car runs and responds fine as if she's warmed up a bit.?
It doesnt stall and idles fine and there is no dash light etc. I have changed the MAF recently, however with the old MAF the symptoms were just the same, so I think I can rule that out.
Could it be the upstream oxygen sensor?
Anyone else have this problem?

Thanks