Bad stutter in third during wot

[1998eclipsegstdsm]

since I Did an exhaust my car will (my best explanation) stutter in third while under wot. The best way to explain It is that it is like when someone doesn’t know how to downshift and the whole car dips but at about 4K rpms and wide open

 

[Mello]

Not much info to go with. Start with your plugs, are they in good shape or new, are they gapped correctly, are they NGK's?

 

[Vegas Smith]

Maybe fuel cut or something.

 

[Bo0sTeD 4G63]

Do you have any type of engine management system? If so you could see if it’s either a Fuel cut or ignition break up.