You can do a better job squeezing up the chest and getting the back tight prior to pulling, and you need to get the bar the correct height off of the floor, but these issues would not account for your sudden failed progress in my opinion. Maybe your grip failed you for your single rep of 290lb??
How often are you deadlifting? How was your recovery (diet, sleep, stress, etc...) after your last workout when you deadlifted?
As for squatting more than you deadlift, post a squat video. Chances are you are squatting high.