Ford Mondeo 1998 Wont Start when wet?

When it rains or is wet my Ford Mondeo wont start. It kicks like a mule but only turns over.

If I drive through a puddle the negine starts to sputter like an ass then dies on me.

I've had the crank shaft sensor replaced, the cam shaft sensor replaced, starter motor replaced, some rewiring, HT leads replaced, battery replaced.

All this and it still does not run when it rains or gets wet.

Does anyone know what this might be and how I can fix it without costing an arm and a leg.