Just recently pulled my dad's old a4 out of the shed, where it sat for about 7 years. After getting it checked by a mechanic and passing an MOT it still seems to be quite down on power, now as I hadn't driven the car before I don't know what it used to be like before it went into the shed but it still seems quite sluggish. The issue is there's no response at all until about 2500rpm in which something kicks in and the car takes off. I do know there was an issue with the turbo and that was replaced so maybe it's that but I'm unsure. Any help would be greatly appreciated