2001 buick regal w/ bad ignition coil and clogged catylitic conv.

sounds like a bad clockspring 1998 BUICK REGAL 3 8L V6 Supercharged Air Bag Clockspring RockAuto

I am assuming you have the 3.8 ltr... non supercharged? I would have your coils and ignition control module checked, thats first. Usually, when the hesitation and or misfire occurs only during acceleration, the issue normally lies in the secondary ignition system. Meaning, ignition wireset, or coil pack or ignition control module. Is your check engine light on? I would have it scanned at a local parts store for any codes that may point you in the right direction for repairs. Or you can take it to a shop and have a diagnostic scanner hooked up and go to live misfire data, and figure out if it is misfiring, and on which cylinder the problem lies. Any other things I can assist you with, please dont hesistate to ask!

There are usually at least 2.
One is upstream, meaning before the cat. conv, the other is downstream, which is usually in the cat or near it

Spark Plugs should be replaced every 3 years,
in my world

Wires are only replaced after ten years or more, or when they
fail, on a secondary ignition test,not just so you can be sold
something called a tune-up that really is non existant

Plugs seldom misfire,they just wear down & stress the ignition
system

A misfire is caused by ignition coils,modules,vacuum leaks,
egr & such

Just have to go thru all the scan tool data at a repair shop &
on a road test, then component test or look for the obvious

Priority Action Part Type Cause
1 Inspect Catalytic Converter Clogged or Faulty Catalytic Converter.
2 Inspect Piston Ring Set Worn or Broken Piston Rings.
3 Inspect Distributor Worn, Damaged or Faulty Distributor.
4 Inspect Distributor cap/rotor Worn, Burned contacts

Priority Action Part Type Cause 1 Inspect EGR Valve Improperly Functioning or Faulty EGR Valve. 2 Inspect Fuel Filter Clogged or Dirty Fuel Filter. 2 Inspect Fuel Injector Dirty or Worn Fuel Injectors. 3 Inspect Radiator Cooling at System Clogged. 4 Inspect Timing Specification Incorrect Ignition Timing. 6 Inspect Coil -Ignition- Faulty Ignition Coil.

the catylitic converter will do that if it is bad

Per your description, it sounds as though you have a stuck injector. I assume you have a service engine light on. Take the vehicle to your local Auto Zone or Advance Auto Parts and ask them to scan the car for trouble codes, they will scan the vehicle at no charge to you.
Write the codes down and respond back to this post and we can get started.
Let me know.
Regards,

Yes, I would start with the coil and plugs.

Could be a plugged catalytic converter or a plugged fuel filter, run an exhaust back pressure test, any muffler shop will do this, most times for free, the other thing to do is have the fuel pressure tested under a load, also clean the MAF sensor, a little dirt on the sensor wire wrecks havoc, You didn't leave anything in the intake runners did you? have seen seasoned technicians do this more than once.