Pontiac Grand Am is running on only two cylinders

Question: 2001 Pontiac Grand Am is running on only two cylinders...the mechanic I use has tried to replace the coil but it didn't help...he doesn't have the equipment to diagnose...but I feel sure he could fix it if he knew where to go next... Already Tried: replacing the coil...I don't really know what else he did...but the coil didn't fix it...and I had it replaced about 2 years ago so I don't know that it was the problem to begin with...but my mechanic doesn't have the computer diagnostics to figure out where to go next...please give me all options and opinions as to what else the problem might be...it will save me trying to drive it 15 miles (which is might not make) to get to a place that has the computer diagnostics to figure it out... Answer: This system uses both cylinders for the spark in each. If the plug or wire for one set of plugs on a coil is bad, the other won't fire. Change to plugs and wires for the cylinders that are not firing as that is an inexpensive attempt. If that does not do it, the Ignition module is the problem. I strongly suspect the module myself.