u/Like_Zoinks_Man

So I have a 1985 corvette, runs perfect, fresh oil change, plugs, cap, rotor, IAC valve, runs like a top. I’m having a check engine light come on, but only when I’m using cruise control for at least 5-10 minutes. Have no idea what it could be. Every vacuum line I can get my eyes on seems fine, nothing broken, or leaking (as far as the eyes can see) anyone else have this issue or know what could be causing it? The cruise control still works perfectly fine the entire time too.