starting issue

2005 Hyundai Accent
70,000 miles
manual 5 speed

So I bought the car from a dude in Texas about 2
years ago. There were no starting issues within the
few months I owned the vehicle until it randomly
began to act up. The starter will engage and crank
the engine but it will not run. However, the car will
start normally occasionally. The battery is new and
the alternator has passed a test. Also, the vehicle
will sometimes stall when idle. Most of the time I
start my vehicle by spraying starting fluid in the air
intake which always works.

This has been an issue ever since it began and no
one seems to know what's wrong. I want to also
include that over the winter when tempatures
dropped the vehicle never once failed to start, but
as soon as the tempatures rose to 60 and above the
starting issue began again.

weak fuel injector?
electrical?
MAF?

Any input would be greatly appreciated.  

Forgot to mention my car will always start when I
roll it and pop it into 3rd.