Looked for vacuum leak but never found one, a few of the hoses look suspect old and brittle looking but no leak found. tried listening for leak with a stethoscope definitely no big leak. Would a small leak cause problem and what's the best way to locate?
Truck has about 100 miles on it since last code if it does it again I will swap cop with another cylinder and see if misfire follows and try to find better way to locate vacuum leak.