ENGINE RUN ON

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I am working on a 20k mile L78 Camaro. The car always ran fine but the carb was leaking so the owner rebuilt the carb he also tuned it up points plugs cap wires. The smog was off the car so he also reinstalled that. He brought it over because it now runs on when it gets hot.
Heres what i did checked timing and set it at 4 relaced the carb with a known good one replaced heat riser because the old wasnt opening and disconnected hoses at the check valves and plug them The car still runs on any suggestions.