OK, how about the possibility that it is somehow related to the fuel pump not working correctly when cold? Or a seal
Quote:
somewhere along the fuel line that's leaking air into the system whilst cold?
The thing is, maybe the rattle isn't only happening between gear changes or at idle/overrun, but maybe it is also happening under load and we can't detect it then with all the other noise? Once recently I was accelerating uphill about the same distance from home when the rattle usually occurs, and I got a brief, distinctly harsh spot of revving - like the rattle only different because the driving scenario was different.