Having a 'tense grip' will slow the jerk down as your tense and your arms muscles will have to untense first, relax then tense, and instead of going from a relax to tense state.
A few coaches I've heard say have lower elbows to push on the bar but this is wrong. You should push yourself under the bar and start the push just before you finish the drive up after the dip. The 13k word document I read about how to Jerk said so! But with higher elbows there is less distance for them to travel to lock the bar then lower elbows...but it's going to be pretty f0cking m00t man...
To the OP:
Grip the bar in a front squat position. Raise one elbows up and the other down. Repeat for 35reps increasing range as and when they feel warm. Do this daily for 6 weeks. You will improve. I can grab the bar fully with high elbows, no big deal, but I choose to grab the bar with a fairly relaxed grip instead with high elbows as I have a habit of leaning slightly forwards when I Jerk heavy.