2002 Hyundai Accent losing power / revving high

I recently put a lot of money into my car to
fix everything. I finally got the check engine
light to shut off. Yesterday, I made a 260
mile trip and my check engine light came
on again. On the way to my destination, my
car felt like it was losing power. There were
a lot of mountains in the area so every time
I had to go up a hill, I would accelerate but
all my car would do is rev up to 3 or past 3
but wouldn't go any faster. It has been
doing this since I bought the car but not like
this. I realize the car is old and has high
miles but I have literally babied it since I got
it. It's a 2002 Hyundai Accent and has
184,000 miles on it. The code that came up
when I checked it was P1402. That's one of
the codes that was coming up when I
bought the car but I had fixed everything.
Replaced the purge valve and DMTL along
with the harness. Someone please tell me if
they know what the problem can be? I've
been through hell and back with this thing.
Please don't tell me there's no hope for it!