I thought I'd post this for future reference for anyone who experiences the same problem, mine is a 2002 JTD115

I took my Stilo out yesterday and it was absolutely tipping down with rain.

After 15 or so miles the engine started losing power jerkily, cutting in and out, and the "Engine Fault" warning kept flashing up.

I pulled over and it idled fine and seemed to rev up okay.

Started off again and it seemed fine....until a couple of miles down the road when it started again.

This time I pulled over, it idled fine, but there was no throttle at all.

To cut a long story short, it was the D4 connector under the battery fuseboard.

I had some electrical cleaner in the boot due to all the other connector issues I've had, sprayed both halves of the connector, fitted back together, and it cured it straight away.

Lesson being.....if you haven't already followed the D4 connector guide on here.....do it now before winter arrives in proper.

https://www.fiatforum.com/stilo-guides/99828-d4-connector.html