Here's my problem, just bought my Elantra, it has 128k miles, 5sp, 2.0ltr
Live in Phx. Az. Temp hot 100+ degrees

Drives great and everything seems fine but when driving for approx. 40 minutes it will suddenly loose power like the engine is starving for gas. It does not stall.

Put it in neutral and step on the gas, it will rev up and then loose power, if I keep my foot on the gas I will here a popping sound from under the hood, something like a missfire.

The first day this happened, no warning lights. I got it home let it sat over night, drove to the mechanic which was 30 mins away and it ran fine, no problem and no codes. He drove it, no problem. Took it home, went did some running around with it 20 minutes and started heading to work. I was on the freeway for about 20 mins and bam it happened again, same issue.

This time it did show "check engine" and I towed it back to the mechanic. He told me the code said "Air Fuel something" I don't remember exactly.

Couple hours later I called and they said they are putting a new "Coil Pack" and that will fix it.......

I haven't gotten the car back yet so don't know it that fixed it yet.....

I've found similar issues like this on the web but no real solutions...

Help

 

Well if the coil pack is cutting out then one or more spark plugs stop firing, that would cause a real loss of power and drivability.....