Hyundai Repair: 2001 Accent dies in hot weather, air flow sensor, maf sensor

Question
I have a 2001 Hyundai Accent (manual trans., 140,000 miles). Last summer, it
started to stall on me after being driven for a while. It either will stall every
time I hit the brake (and I have to pop the clutch while rolling, no problems
while accelerating or rolling. Just when I hit the brake). It'll also stall
immediately after starting. No problems all winter, but it started again on an
80-degree day. Check Engine Light has been on for a while, but the last
mechanic didn't receive any codes.

New mechanic was able to get codes (sorry, don't know which ones) and says
he thinks I need a new MAF sensor. Last mechanic replaced, but with a
refurbished one. Does that sound like the problem to you?  

Answer
It's possible the air flow sensor is the problem, but there are many possibilities.  

If you can follow up with the actual trouble codes, I can determine whether they may be related to the air flow sensor.  Chances are very good that the reason the check engine lamp is on is the same as the reason your car is stalling.