My buddy had the exact same problem and ended up getting 6 new injectors. It would not start with the temp in the teens and not plugged in. As far as I know there are only two products one the market that read rail pressure, quadzilla and DiPricol. The DiPricol will not read during cranking, only while running. If you do end up getting injectors put in, I would HIGHLY recommend another fuel filter down to 2 micron. The factory one is 10 micron, you can get a 7 micron, but at 10-24,000 psi rail pressure any debris ruins injectors. I have a 2 micon CAT filter between my factory filter and CP3, so far no problems at 88,000 miles.
Using a small bit of ether is a good trick to check if its an injector issue, I did that on my buddys truck and it started on ether every time.