Originally Posted by
PMDL
Two things:
1) Sometimes deadlifting once a week gets to be too much to keep the week-to-week linear gains going; however,
2) That's also a helacious squat workout you just did before hand, and I'd almost guarantee that the fatigue is limiting your pull.
I don't think people need to think about completely dropping the pull from training in favor of special exercises until they're very, very strong. I'm talking well over 500 and probably over 600 before you'd even need to consider it.
I'd look more at fiddling with the loading parameters, specifically not kicking your ass with a squat workout before you try a deadlift PR. If you're set on doing squats, either do them light or do easier front squats. If it were me, I wouldn't squat at all beforehand.
If that doesn't work, then go through the rest of your troubleshooting process.