Rough idle

My 1993 safari 4.3L vortec idle is fine when is cold when it has warmed up it is rough it dose not quit after replacing leads rotor and cap also replaced fuel injector
assy checked for Vacuum leaks and fixed them it still runs rough after warm up the plugs were in good condition however one side the plugs were full of suet( indicating rich mixture) the plugs on the other side were fine still runs rough would you have any suggestions