Why does my car miss when accelerating?

why does my 95 ford escort miss when accelerating, untill it reaches 4,000 RPM then it pulls strong. but if i accelerate very slowly it runs fine. i just changed the plug wires because they were cracked. and also have filled up with high octane and used injector cleaner and water remover. i am going to put new plugs and fuel filter on im sure it needs them, but do you think that will solve my problem?