94 Sonoma, engine light at constant speed
 

i have a 94 sonoma with a fresh rebuilt motor, and the engine light comes on when i maintain any speed over 60 km/h for any length of time. If i turn the truck off and restart it the light goes out. The truck runs perfectly, and gets regular maintenance. What could cause this?

Have it scanned to see what code comes up. I had one doing the same thing and it was an EGR issue.