s10 random misfire

last 4-5 years the truck misses real bad when going up long hills or when accelerating to 65-75 mph on the interstate. the SES light blinks for a few seconds and then comes on solid. after a couple of days, the SES light goes out. been to the dealer several times and all they said is that the random misfire code is in the computer and they cannot duplicate the problem. other than going up long hills or when first accelerating onto an interstate, the truck runs great. could there be trash in the gas tank or could the fuel pump be going bad?

thanks

Usually a random misfire can be due to a bad plug or wire. A simple tuneup may be the fix.