Slight hesitation at 2,000-2,500 RPM with power key on

[Vette73]

Just had the plenum and injector housings ported...

If I get into the throttle hard the car has a slight stumble at 2,500 RPM around..
I really can't classify it as a hesitation, it's like the car feels like it shuts off for a split second than it catches.......If I'm driving " normal" it really doesn't do it, just when I really lean into the gas...

Does not do it at all when the power key is turned off....Other than that the car has plenty of power and does not stumble at all at high RPM just down low like I explained...