Starts fine, misfire cold, then fine - ideas?

[bherlingo]

Well the issue is definitely EGR valve - I took the air intake connected to the EGR off and noted the position of the butterfly flap. It was open until I started it up whereupon it immediately closed. On tickover as above, it was happy - clearly getting enough air for the low revs - then when revving it falters. I held the flap open with a screwdriver and it immediately ran fine. I've disconnected a vacuum pipe running to it and it now stays open, and runs fine. My guess is that one of these vacuum tubes is connected wrong in the engine change - I need to get a look at another DW8 setup to check/correct it, I doubt a manual would show the layout fully.