1996 7.3 powerstrokerunning ruff

I am new to this post. I have a 1996 F 250 with a 7.3 power stroke diesel. My first diesel. My truck runs ruff, has a check engine light on put i can not pull a code. If I clear the codes the engine shuts off I restart and the truck runs perfect for 20 seconds, starts to miss and the check engine light comes on within 5 seconds of starting to miss.
I started it up, it ran fine took it for a drive within 2 minutes it started to loose power an run ruff. I changed the fuel filter. No help.

Please help, i need the truck

Butch