1990 3.3 rough running until wamed up

does anyone have any idea what would cause my 3.3 to run rough until it warms up.it backfires and acts like it wants to die.i have changed the coils,coolant temperature sensor,map sensor,tps sensor,and have checked fuel pump pressure,replaced fuel filter.i have also changed plugs and wires,but it still runs rough.any help would be greatly appreciated.