Engine has a miss

i have a 1994 chevy astro van 4.3 liter v-6 f.i. it has a miss on one cylinder (number 5). it had a reman head put on that side. it was replaced because the valves were stuck. it had new push rods and lifters installed also plus new plugs wires cap and rotor.checked comp. it is good (130).timming was checked and set.any ideas thanks.