Last time I had a hesitation problem, it was my plugs, and they had hairline cracks the length of the plug in a few of them.

Ran fine, but after 3500 RPM would snork, pop, bog down.

Also, what are top choices of plugs for a 1990 carbed 454 magnum with CMI headers??

The last guy that installed them , tightened them while holding the wrench at the wrong angle ...or didn't use a spark plug socket ...

It was me, and especially since a few were cracked I was very carefull, and used a spark plus socket

They have lasted 2 years, and just started snorting, poping and bogging last weekend. (I thought is was the fuel water seporator filter, but that was not it) and new carb was installed a couple years ago as well.