V6 3.0L Miss in cyl 3

I have a 2000 Saturn LS2 V6 3.0L. I have a miss in cyl 3. I had the heads worked on this engine. All valves were replaced because the timing belt broke before the recommended 100,000 mile replacement. The coil module was replaced on the 1,3,5 bank. The brand new Bosch plugs were switched and I still get the same The code for cyl 3 miss keeps coming on. Is there something else that could cause this miss and erratic driving. Another piece of info. One oxygen sensor was replaced after rebuild of the cyl headers and the car ran very well for about 6 miles with good power and no miss. When the car was restarted the miss came back. Looking for suggestions. Could it be the intake manafold leak causing cyl 3 to miss?

may things can cause a miss, to many to count.i would start by inspecting the plug for abnormal wear and listening for injector tick

these are the checks right out of the manual


Check secondary voltage components for corrosion of EI module coil towers and spark boot ends. Check secondary voltage using a spark plug tester and jumper wires.
Check spark plugs for cracks, broken insulator or improper gap.
Check wires for chafes or cuts.
Check for low fuel pressure and fuel quality.
Perform injector balance test to test for clogged injector(s).
Check for proper valve timing, broken valve springs or sticking valves. Perform Compression test.

It was fuel injector not connected properly