Do I need new motor mounts?

Hey guys, I just bought a 93 coupe and according to my friend, it might need motor mounts. I figured I would post on here though and see if I could get any more opinions. The car starts normally, but then as soon as I begin to drive, it makes a clunk noise that feels like it's beneath me almost and then the engine check light comes on. The clunking doesn't continue, it's just in the first/second gear, but why does it make the engine check light come on? Whenever I turn the car off and turn it back on, the light is gone, but as soon as I begin to drive and that clunk occurs, the light comes on. As far as I know, everything else is fine mechanically, the car seems to drive just fine, but I just got it so I haven't been driving it for years and don't know it like the back of my hand. Car only has 100K miles so hopefully it's nothing serious.