Considering the age of your bike and the fact that you are a recent owner not knowing all that has been done to in its 34 years of previous owners, I would consider
a general update of the bike. I have an '88 fxstc. Had it since I bought it new. A few years ago, I updated everything. I discovered that age and use did a lot to degrade parts and reliability in spite of very faithful maintenance. Did a top end, replaced oil and fuel lines, replaced input manifold, replaced ignition, rebuilt the S&S carb, replaced the stator, refreshed all the wiring, replaced pinion bearing and cam, replaced primary chain, brake pads, etc. The bike runs better than new now.
Sometimes it's better to refresh an older bike rather than doing trial and error trying to fix a mystery problem or problems. You might actually find the cause. But it usually won't be long before another age-related problem shows up and leaves you on the side of the road again. JMHO

 

Thank you I was planning on doing a good amount of refreshing through the winter on it I was just hoping to solve the running issue to get a few more rides in this year

 

Using the poll to ask for maintenance help is not the way to go. Model, year, and a thorough explanation of the issue will usually be the best way to get what you need.

Good luck

 

Check coil?

 

I've got an 89 FLHS and once it would sputter and cut off and on then backfire several times while cruising and finally found a cell in the battery was shorting out and replaced it. No more problems. It was really unusual and hard to determine bc battery initially tested good but second test it crashed. Good luck1

 

Mikuni 40 or 42

 

It may or may not help you trouble shoot the issue, but I often find it useful to add a clear fuel filter to the line to "see" that fuel is present.

Might be as simple as plug wires. What do the plugs tell you?

Somebody mentioned they had battery issues. My sporty is notorious for working a connection loose at the battery, it will run just as you describe.
It became so common that I check the connections every oil change.

Good hunting

 

Avoid in line filters, they will cause operability issues.

Clean the needle and seat in the carb.

 

When you fiddled with the idle mix, did you make the carb richer or leaner. Are you running rich jets?