FPR power (30) comes from B+, and is always hot. The fuel pump and the WUR are both powered from 87 on the FPR (switched power).
The WUR could be a bit out of calibration and raising the control pressure too much.
Try taking a 1/4 turn rich (CW) on the main mixture screw. If that cures the stalling, consider a re-fresh of the WUR, OR, just run it that way!