I have pac's like you - they come and go just the same. They are most definitely much worse if I'm gassy, to do with the vagus nerve, I think - there is quite a lot on that around. I don't know which causes which, but there IS a big link. It's horrible - I'm going through a bad patch now and I hate it. Been taking flecainide which has helped a lot for 2 or 3 years but now it all seems to be building up again. Very hard to ignore when it's happening.
Has you PAC been diagnosed by a doctor? Do you take any medications? Sometimes symptoms are side effects from medications.
My atrial problem is fibrillation, and it never gives may any indigestion or upper respiratory gas - but it may be it does in some people. Be sure it isn't from something you ate or drank, and if it is try to avoid that in the future.
This post will "bump" you to the top of the list again, perhaps someone with PAC experience will reply.