1992 Buick Century car chugs with temp light on

I just did an oil change on my car last week. It was all fine and dandy then I took a trip up a hill and half way it started to chug and the engine light flashed along with the temp light. But it would only flash when the car was chuging. The temp of the engine was at operating temp says the gage inside. I pulled off the road to let it cool down and then continued. It worked for 3 min but then started to chug agien.