I get this sometimes but I've got a K&N 57i cais whereas you have a panel filter so that won't be it. As Ade_cx said check if its not the ESP (traction control) throwing a wobbler. Sometimes on a wet road even in 4th it'll kick in for me and gives this hesitation feeling around 3000rpm when the car hits full boost/power. It'll flicker on the dash as a yellow car with tyre marks following it.
Or as others have said could be the plugs. Was it doing this before you changed your plugs or has it just started recently?