gpz750r 1984

My gpz750r (1984) starts to feel sluggish as I increase speed.Fuel seems to be too rich or air flow problem, but.. pretty sure I've checked all the obvious ie;carbi,plugs,fuel ,compression,etc.Can anyone help with diagnosing this problem?I'm not riding bike too hard or expecting too much out of it! It feels like when I open her up she floods or loses it ..bit hard to tell.Anyone have similar problem or have gpz750r that can offer advise or info on it?Any advise in maintaining this bike would be appreciated .Thanks.