1988 Delta 88 no spark on 1 and 4

Hi, I have a 1988 Delta 88 with a 3800 v6. I'm not getting any spark on the number one and 4 cylinders. I've replaced the crank sensor, cam position sensor, coil pack and the module underneath of it. Today I replaced the ECM, still no spark on the same 2 cylinders. I've checked for spark at the coil pack so I know it's not plugs or wires. I'm hoping someone here can give me a new idea to solve this problem. I would greatly appreciate a push in the right direction. Thanks very much.

Welcome to AF, usually caused by icm, but look closely at the reluctor on the crank balancer. Remove the balancer look at the reluctor wheel. Of course you need the proper puller.

Thank you for the reply.
I had the balancer off when I changed the crank sensor but didn't pay any attention to the reluctor. I'll pull it off again tomorrow if I can find time. When i do what exactly should I look for?
Thank you again.

Bent, loose or mispositioned reluctor segments. Also make sure the balancer hasn't slipped around the inner hub.

Pulled the balancer off nothing out of place. The reluctor wheel was a little gummy so I cleaned everything up with some lite sandpaper.Put the balancer back on still no spark on 1 and 4. Any other thoughts. Thanks I really appreciate your time

A defective new icm would be rare. Did you look closely at the balancer they are famous for the outer ring slipping, usually we make a mark across both to monitor if it has. moved. Try and get an obd 1 scanner and see it you get a cam sensor signal.

I pulled the balancer off again. Their is no mark on the balancer that would line up with keyway to tell for sure if it has moved. But I've inspected it closely and everything seems to be in place. No movement, no rubber sticking out anywhere, no gaps, everything looks as it should. The vehicle has 62,000 original miles on it. Would a slipped outer ring normally be an issue with a low mileage car? Haven't had a chance to get an OBD to check for a crank signal.

Age and heat are the enemy for the balancer, you can make a mark across the 2 sections so you can tell if it slipped, common practice. Cam signal is needed in this case as I mentioned