Hi, my car started to jerk when shifting from 1st to 2nd, no other gear change including down shift. It only jerks when I accelerate at 2-3k rpm. It doesn't jerk at all first thing for about first 20 min. I had a transmission leak from the cooler lines a while back but I patched it and add fluid, I didn't have any problems until now. It has 120k miles and I think the last fluid change was about 75k miles. When it started to jerk I decided drop the transmission pan and change the filter, put new cooler lines and added 7.5 quarts total of Dex 3 mixed with a jug Lucas transmision fix. I only found regular wear dust on the pan magnet. I drove for two hours (country roads occasional stops) and it only started to jerk at the end. I let it sit for an hour and it was jerking, there's a narrower rpm band where it jerks now and it isn't as hard. After it sits over night it changes smoothly for a while. What could the problem be? When it jerks if feels like it changes to second but doesn't engage right away.