My Mazda is missfiring on cyls 4/6 after an obstruction in the induction system on 2002 Mazda Tribute

the Cats failed and caused a loss of power exctely like limp mode but no codes, after clearing exhust restrictions and re testing the high pitched squeel like belt slip had gone and the engine runs but missfires on cyls 4/6, swapped coils and plugs fitted new injectors and manifold gaskets still missfiring now suspect Ecu ? have strong spark at coils and I believe injector pulse is at the same source as coil pulse LOST FOR IDEAS ????

Asked by for the 2002 Mazda Tribute