Hi!
Something similar is happening to me, only in my case it seems that the weather or atleast the fuel has to be fairly warm when it happens. As you stated the engine sort of staggers in third gear at WOT or near. The fuel pump may be the culpert but what about the fuel pressure regulator. Maybe we ought to change the regulator before changing the pump. Also, I think it might be a good idea to have the fuel system pressure tested before shelling out for either the regulator or the pump...
John
