Bad part from supply is possible but not very likely IMO.
Power would be next thing to check. Check to see how much power dips while accessories are turned on and off. You'll need to override the pump motor via the connection at the firewall. If you're not sure what I'm talking about, JRichker has a pictorial diagram of it somewhere. I'll pull one up if you need it or can't find it.
Unless I'm missing something (not at all unlikely) this would be the last thing that we can really check without taking something apart and/or spending money.
Even though you have the correct diagram (the one indicated on paper) it doesn't rule out that it's not a large enough ratio. That I think, would be the next thing to look at BUT ONLY IF you're planning on skipping the 42's and tune.
Skip over any tuning system that is a TwEECer or even remotely like it in terms of user tuning. I consider myself to be a pretty tech savvy person. To make a really long story short, all I wanted to do was set that POS on-top of a fence post and shoot it till I was out of bullets. The hardware is all very first gen and the software is the geek project of a group of guys who swear it's the greatest thing on the planet.
If you want a another effin hobby. Buy a TwEECer.
After that experience, I had it chip tuned on a real dyno, by a real tuner who had specific experience with the equipment he was using (these are ALL qualities that I did not possess). I gave the man my $500+ and drove that mofo all the way home (2 hour drive by sane people) giggling like a bich who just smoked pot for the first time.
Since then, I've used an Anderson PMS on a couple of different cars. Pretty simple beast. That is all.
These other guys will have to get you about MOATS and QH, and all the others. Different features, different abilities, different ways of doing things. Some are verynice and a lot more advanced than the two systems that I've used.