1989 Festiva carburetor runs o.k. at half throttle but poor

[Bbarker]

My 1989 festiva revs fine in neutral(is a stick shift) runs o.k. at half throttle or so but when I give it full throttle it kind of sputters and won't go past 50 miles and hour until I let off the gas then it slowly climbs up to speed. I am a mechanic and have replaced the timing belt and spark plugs. Not for this concern but because I just purchased the car and wanted to do some preventive maintenance. Don't know if it is carb issue or something else I am new to these cars and any help would be greatly appreciated.

[Fordverde]

Check vacuum hoses, if nothing is broken, then the gas level on the carb is too low, adjust the float.

[FestYboy]

how 'bout this, your secondary is opening, but the main jet isn't feeding fuel. that would cause a bog (too much air, not enough fuel). or on the other side of things, you have a fuel leak when the secondary kicks in and it is allowing too much fuel (secondary butterfly isn't opening, but secondary main circuit is allowing fuel). check your fuel pressure first, then manualy activate the secondary at idle, note what happens.