Car is an automatic, 3.8 V6. After a trip of 170miles or so whenever going from 1st to 2nd there is quite a 'jerk', and a smaller one from 2nd to
3rd. I've found I can make this stop by taking the gas cap off for about 15 seconds or so then everything is fine. Another problem I've noticed is that sometimes up until about 65mph the car will run rough or hesitate, above that it seems to run fine. I don't notice any drop in rpms though. The converter was just replaced last year, the car has a bit over 84k on it. Any ideas on what to check?Thanks Chris