Car Surges sometimes while accelerating

My car has automatic transmission and I’m having this issue but it’s not frequent, I’d say 3 to 4 times a month it happens, that while driving when I push brake and car goes to 20 km/h or around that, after that when I put my foot on accelerator nothing happens neither RPMs goes up nor the speed no matter how hard I push the accelerator, it seems like car is surging for power or fuel, it happens like 4 to 5 seconds only and then everything seems like normal, then RPMs and speed goes up. I didn’t see any engine or other light comes on while having this issue.

I talked to couple of mechanics, one of them said it’s very difficult to identify a problem which happens 3 to 4 times in a month only.
The other mechanic asked; is there any kind of light turns on while having this issue, when I said no, he was also confused about the issue.

Can anyone suggest me the solution or from where to start to identify the problem? Maybe the Spark Plugs (they’re at 30,000 km) or the Fuel Pump and by the way, the filter of the fuel pump in my car is not separate, it comes in the fuel pump.

hyundai sonata

Model-Year, please?
CSA

Hyundai Sonata 2011

The problem might be with the electronic throttle body circuit.

Instead of a cable connecting the throttle pedal to the throttle body in your vehicle, it has a throttle pedal position sensor, https://www.rockauto.com/en/moreinfo.php?pk=7493724&cc=1446207&jsn=383&jsn=383 which sends a signal to the computer, and the computer operates the electronic throttle body, https://www.rockauto.com/en/moreinfo.php?pk=8453436&cc=1446207&jsn=350

Tester

so you’re suggesting me to start from replacing both of them? Can you tell me how much will be the average cost with original Hyundai part?

I’m not suggesting anything of the kind.

You asked for a suggestion where the problem might lie. And I provided a suggestion.

Since the problem is so intermittent, you may have to wait until the problem is more prevalent to pin down the cause.

Tester