Before you investigate the FP do two things:

1) now and the next time it stalls pull out two spark plugs, what color are they? If they're quite black then I bet you've got yourself an air leak. I'm not fortunate to have a turbo but I know mine shows 21 at the vacuum tree. I can't remember what yours is supposed to be, maybe someone else can let you know.

2) How often does this occur? If its every hour or so then try jumping the relay to see if it stalls. If its less often than that, either you or a helper needs to listen in the trunk for the FP when you turn the key to restart. If there's nothing its likely the FPR. You might want to listen there a couple of times when it is working correctly so you know what sound you should be hearing. I'd investigate the wiring of the pump last, as the FPR is much more likely to go.