al45

My one engine will not rev above 3000 rpm the engine will buck. I have changed the alt the slave solaniod and still no change i have also change the fuel filter the other engine runs fine.The engines are the 488's that mercursier made bake in the 80's. Iam not sure if if i have afuel delvier problem or not and at this piont I am concern that imight have a morgsr engine problem. does any one know what the next step should be?