If this is a new condition, it could be a clogged main jet or as suggested above a sticky slide. Either way a good cleaning will resolve the issue. If this condition has alway existed, you have a lean main or needle (depending on how wide you are opening the throttle). At what throttle setting 1/2, 3/4, full) do you notice the lag?

Actually......you should not get in the habit of "cracking" open the throttle - but rather rolling the throttle on.  When you instantly open the throttle the vacuum in the venturi drops drastically, and the ability of the carb to pull fuel through the jets is compromised.  The CV (Constant Velocity) carb is supposed to help keep the engine running well when this condition occurs by sensing the drop in the vacuum and it drops the slide/needle to keep the air flow high enough to sustain the vacuum.  So....when you crack open the throttle the slide drops, and gradually raises as the engine responds and builds up adequate air flow to allow the slide to rise up to the full throttle position.  Should this take 3 seconds.....probably not in an engine that is jetted properly - but there is some lag in the CV carb when you make an abrupt change in the throttle position.

In a non-CV carb the drop in vacuum sometimes can result in so low of a vacuum that the fuel flow stops - and the engine just coughs and stops running until you let up on the throttle a bit.  This is especially true on modern engines that are jetted really lean to comply with the emission requirements.  The CV carb design is used to help make a smoother running engine, and correct for an over-aggressive application of throttle (just like ABS brakes correct for too much braking or Traction Control correct for too much power).  However the CV carb is mechanical and not digital electronics....so there is a bit of a lag to be expected.  (Proper jJetting could however help to shorten the lag).

Thanks for all the advice

Kinda depends on the gear/rpm you're at when you nail it. If you're just rolling along and at the lowest speed you can be at IN That Gear, You might wanna drop a gear and pin its ears back. .but the Seafoam treatment for a coupla tanks won't hurt.

I'm with Versy.  I hope the oil was checked.  Could be an engine with a gallon or so of gas in the oil and very little lubrication.

Oil level was and is good. Just changed over the weekend