Hi I have had my Subaru Legacy B4 engine changed. After 1 week the turbo gave up found out for the guys who replaced the Turbo that the Pipe fitted with the new engine was not correct one and it was not fitted to the turbo. Got the Pipe changed + the Turbo changed. After the changes the car worked really good for 3 days and then now it has issue when I put speed the car jerks and seems that it will stop. This happends when I put in a sudden speed example getting into freeway or passing another vechile.

Can some please help on what would be the issue.