I have a Heil furnace that won't stay lite.
I have replaced
Aced the pilot assembly and that hasn't worked
What do you suggest

You can review the stickies HERE. (https://www.askmehelpdesk.com/heating-air-conditioning/heating-cooling-maintenance-repair-troubleshooting-faq-northerheat-58313.html) Dirt in gas orifice, thermocouple, no signal from gas valve to the assembly heat sensor not properly aligned. Improper air flow..

https://www.youtube.com/watch?v=o3rfqQ0fgjw

https://www.youtube.com/watch?v=PiCmfW1rTRY

Easy to see why repair techs make the big bucks.

The worst thing you can do is just start replacing things. Could be a roll out switch, a hi limit switch, a bad thermocouple. Heil makes a lot of furnaces. IS there a control board with a diagnostic LED? Must be fairly old if it has a pilot.