2000 Honda Accord Engine Light On After Losing Power

Yesterday, I drove my car 7 hours over several Colorado mountain passes. The car started to "chug" (act as though it was not getting gas or losing power momentarily) about 4 hours into the trip. It was very brief and only happened 2-3 times during the trip.

Just before I arrived home, the problem became worse and the engine light came on. I was driving up the last hill to my house when the car lost power and then regained it.

Please note that I had slowed my speed. Also, I noted when driving that the problem seemed to occur when I slowed or was idling.

I had a loose fan belt a few months ago but otherwise I have had no problems with this car and have had regular maintenance done on it. I did notice that the fan belt might be loosening again when I checked it recently.

What could the above problem be related to?