95 Buick series1 3800 supercharged. It idles and runs well under light acceleration but if you step on the gas, it sputters and misses. No codes showing up. Any ideas are appreciated.

How long since last tuneup?
How old is fuel filter?
Is fuel pump still factory?

A new fuel pump replaced the original almost a year ago. The previous owner had replaced the wires and sparkplugs. I just picked up a fuel filter and haven't put it in yet. It seems the problem is worsening. I'm not sure whereabouts the filter location is on my 1993 Olsmobile 98 Touring Sedan Supercharged. The motor was replaced with a 1995 Buick Park Avenue Ultra Supercharged many years ago.

I just fixed a similar issue on my series 2 3800 in my park ave. Mine would also not give a code unless I kept the peddle down and let it keep misfiring for a minute. Then it would give a random misfire code (P0300) or something like that. Mine had also had the plugs and wires replaced recently by the previous owner but they used budget Autolite wires and Champion plugs. I replaced the wires first with OEM AC delco wires and that took care of the misfire 100 percent. Then I replaced the plugs anyway since I already bought them. I used AC delco plugs as well.
If your car has anything but AC delco wires on it I would recommend starting there. I bought mine from rockauto.com for a decent price. There is a thread posted not to long ago about this issue I had.

This was going to be my exact advise, for the same reasons. You may not know what brand/model of plugs and wires the previous owner used. Misfires (which is what your car sounds like it'* doing) are usually caused by plugs, wires, or ignition coils. GM cars seem to like ACDelco the best, which usually falls in the middle of the pack price-wise. I believe many ACDelco ignition parts were made by NGK, so those would probably be fine to use too.

Check Rock Auto, and also parts store websites like Advance Auto and Auto Zone for any promotions you can use (they often run 10-20% off deals)... order online and pick up in store, best of both worlds because you can save on shipping and return to the store if you have any problems. Rock Auto always has 5% off codes floating around, which will at least pay for most of your sales tax. Retailmenot.com also is a GREAT website for finding current coupon codes for almost any website store that you can imagine.

Here is the thread from my hesitation issue:

https://www.gmforum.com/buick-172/hesitation-while-accerating-55-70-under-heavy-load-308729/