1995 Pontiac Grand Am cylinders

I changed the fuel pump and filter in my car about 2 weeks ago put it back together and drove it for about a week and it was fine. Then about a week ago I was driving down the road and it just lost power and got loud, so I pulled over and looked under it and the exhaust was red hot from front to back so I took it in and they changed the catilac converter and it still got red hot. So they pulled the plugs and changed them. It quieted it down some but it was still missing and only got red right by the catilac converter. So they checked the coil pack and that was good but cylinders 2 and 3 are not getting any spark. So they checked he ignition module and that is fine. We are stumped( thinking it could be wiring some where but nt sure. Do you have any suggestions? The coil housing and the timing also checked out fine.