Check engine light engine sputering

I have a 1995 gmc jimmy. It just threw a check engine light. The computer doesn't work right, so I can't get the check engine light read. It is an intermittent light. I shut my truck off and turn it back on the light goes away. Some times it comes back some times it doesn't. When the check engine light comes on the engine is sputtering. The best way for me to explain it is it is acting like an older car that has fouled a plug. It sounds like it isn't running on all cylinders. Sometimes when I first start it it will sputter like I explained but no check engine light will come on and after driving a short distance it will start running fine.