1995 Chevy Blazer, the engine light came on, and truck is hestitating when driving, why?

My check engine light came on yesterday and the truck is hesitating at times when I am driving it(just started at same time the light came on). The truck drives at a steady speed when it starts acting like its running out of fuel (its full). Am going to change the spark plugs this weekend but don't think that would be the problem. The truck has 107,000 miles on it. I like working on my truck and would prefer to do the work myself just not sure what it might be. Need some idea's from someone who may have had the same problem or helped someone who had the problem. If oxygen senors went bad, it would make the light come on but not start jumping like that I would think. Runs fine at idle speed. Any help would be appreciated with this problem. Can add info. if needed! Thanks again for your help!