1992 VW Golf- I recently had to replace my muffler due to a hole. Even though i now have a new muffler it still backfires from time to time. What's happening? Is something else wrong?

I recently became a victim of bad roads which tore a enormous hole in my muffler.
While I waited for my new muffler to arrive my car was deafeningly loud and would back
fire when I slowed down. I, after driving around embarrassed for weeks , finally was the
proud owner of a new muffler on my Little Go-Go, However it still back fires from time to
time. Not nearly as often but always when i am slowing down to turn and the clutch is
in neutral. Is this a sign of a big issue? Should I be concerned? I want to know ASAP
so i might save my car if possible or repair before further damages.