Personally I'd avoid anything but the Motorcraft COP's Scooter---I've done this swap using Granatelli's and it wasn't an improvement at all. In fact when the weather changes more to my liking and I'm a bit more motivated the OEM COP's will be reinstalled, Granatelli's offered on Craig's List for cheap cheap cheap. From what I've read here on FTE Accel gets a bad rep but I can't speak directly about them.

If your van will be sitting a few days while you're in process of changing the plugs its not a bad idea to hit each hole with some penetrating solution before cracking them that first time---can't hurt. Pay close attention to the video, watch it several times if needed.

As Blageurt suggests be patient---that alone will pay dividends. You can also post this same question in the V10 forums. Doesn't matter what chassis or body they have---the maintenance steps should be very very similar.

You've got a great adventurous spirit so I don't think you need luck---persistence and patience I'll send though.

Let us know how this goes for you!