2014 Kia Rio won't start sometimes and stalls

So I bought my car from a used car dealership and
it only has about 7,000 miles on it when I got in it
March 17th 2016. It's a 2014 Kia Rio hatchback,
just recently we changed the battery, breaks, oil
and everything. (Feb 24th, 2019)

June 1st, 2019: On my trip to Toronto the car was
fine, however; on the way back we stopped at a gas
station to fuel up. Once we filled up and tried to
turn the car on it wouldn't start, by definition of that
I mean we turned the key to start and it just
wouldn't turn over. So we tried once more before
just letting it sit, after about 5 minutes we tried
remote car starter instead. This eventually got the
car running but it didn't sound good when starting,
plus my RPM meter wasn't working and it took a lot
of force on the gas peddle to get it to go.
Eventually we got the girl home and I parked it into
my driveway, turned it off and back on just to see
and it seemed fine. The meter was back up and
she was doing ok.

Now, I just took it out today to get groceries and
get it checked by a garage door codes they said it
was fine. No codes, no nothing that they could see,
even put some fluid in my gas tank to flush out any
bad gas. It started and I was on my way to do the
rest of my errands, but shortly after doing that it
didn't want to start again. Tried twice before letting
it sit, and then 10 minutes later trying again; while
it eventually worked and seemed fine AGAIN. It
wasn't, the first time ever I stalled in the middle of
an intersection and I paniced.

What kind of problem could this be? Is it worth it to
fix? Or should I just upgrade my car with the
dealership I got my car from as they are offering to
do so.
Any advice is greatly appreciated as I am just a
beginner learner at all this mechanical stuff.
Car has about 117,798 miles, have done a lot of
driving from city to city.