Mk4 Mondeo 2.0 Petrol fluttery start

[qube_TA]

When I start it, it's like it's got no fuel or a very weak battery (although it cranks OK), barely runs. Press the throttle and nothing happens. It's like this for about a count of 15 and then it's perfect. Drives fine, doesn't misfire. If you try and set off during the fluttery stage it'll just stall. There are no codes. Swapped out the vacuum module (that was giving a code originally), plugs, fuel filter, battery. But nothing has made a difference.

Oddness. Ideas welcome.