Probably my issue too. I drink a ludicrous amount of coffee a day.
Also, any vape juice with lemon in it seems to do it to me, and any lemon scents or lemon/lime essential oils in the aromatherapy diffuser.
Not giving up the coffee though so I just put up with the heartburn… lol
The latter.
I rarely drink coffee so I know my heartburn isnt from that…ya I know,weird not drinking coffee daily LOL I stopped using the flavors that I thought was the issue for a few months now and no more heartburn.
I know people that don’t drink coffee at all 
Sounds like you found the problem, which is good to hear. And nothing wrong with not drinking coffee. Some of us are java junkies and some aren’t. Different strokes for different folks is what makes the world an interesting place.
Welcome to one forum! 
I don’t think I’ve gotten heartburn from vaping, at least i don’t think so, it’s usually after I eat Buffalo chicken.
When I quit smoking (it’ll be 3 years October 20, 2021) I actually lost almost 70 pounds. Thank you dessert Vapes! I also, at the same time quit fake sugar because it was making me sick to my stomach and bloated. Lately though, I’ve had similar symptoms. Until recently I’ve been vaping commercial eliquid. I’ve been DIY’ing for a few months now. I still vape commercial while I practice diy. A few of my old symptoms have popped back up. I also read above about hiccups. Me too. I’m wondering if it’s the sweetener. I never thought it possible because we aren’t actually ingesting it. 
i am the same, about to the day 
@Lynda_Marie @jinx_d Coming up on 3 years is HUGE. Hope you each have a big celebration in mind !!
i actually had interest in doing it 1+ year before, but something sidetracked me.
and i didn’t know anyone who vaped
My date is Sept 30, 2013. The friend who got me into vaping quit smoking 6 months before I did. He suggested I try it, but I was hesitant until I did quite a bit of research about it. I consider myself one of the lucky ones. Vaped and smoked for 1 day, had 1 cigarette left in a pack the following day Smoked it about noon on Sept 30th and have been smoke free ever since. Very, very grateful. Let’s keep our streaks going strong !!
Maybe treating myself to a new piece of hardware 
Go for it. Rewarding success is important.
Thank you so much 
Nope, you’re not going insane. Some vape flavours might cause stomach acidity and it’s preferable not to take them at all. I used to love the grape flavour, but slowly started seeing heartburns. Never had the idea that something reflexive could happen because of the flavours. Even i thought I was being mad at my family. My brother was the first to diagnose me. He had guessed it by then. So I got myself checked by my doc. He couldn’t find anything so advised me to keep away from them. Now I’m fine. I take strawberry flavoured e-juice now. Things got better anyway.
It’s quite normal to get heartburns if one takes spicy food after vaping or maybe swallowing most of the flavours while inhaling. The flavours are meant to be for lungs and thus upsets the stomach. Also, eating spicy food can increase acid fluxes. A similar thing happened to me a few years earlier. I love spicy food so I used to take some while or after vaping. This has caused me a lot of pain. My acidity troubles gave me a stomach ulcer which is okay by now. People facing these problems might try a bit of a change in their vaping technique. That might help.
Please look at dates.