yer thats too low. should be 42psi (i think) base pressure then another psi for every psi of boost. so at 10psi fuel pressure should be 52psi.
had the same thing when my reg died, on boost it leaned out to the point where it simply couldnt fire, just spluttered.
with the stock ecu the AFR's usually drop into the 10s with higher than standard boost