2005 Toyota Echo Accelerator issue

I have a 2005 Toyota Echo with automatic transmission (100,000 km). Never had any problems with it before today. I was driving it on the highway at around 100 km/hr and went in the passing lane with slow moving traffic so slowed down to around 80. When I stepped on the gas, the car vibrated a little bit, and made an odd sound. The engine revved but did not accelerate. I was concerned so I pulled over, and even when I was on the shoulder of the highway it continued to vibrate a little, and felt “stiff”. None of the idiot lights were on but the check engine light does come on intermittently. It never concerned me because I think it is more to do with the gas cap. Anyways, I turned the car off and drove it home. It appears to be normal again with no accelerator issues but I’m wondering if I should be concerned and get it checked out. Would appreciate any feedback.