IAC maybe?

[ChevyTech]

Originally Posted by wrangler94

Didn't want to leave this hanging and unanswered, but just started a new job so haven't had the time or funds til today to mess with the truck any more. I borrowed an old OBD1 scan tool and drove around with the truck, O2 sensor error (code 13) and code 42, ignition control module failure of some sort. Clearing the code it comes right back too, so definitely going to change that. Thank you again for all the help.

Thanks for the update.
Note: Code 42 will set if the set timing connector is left unplugged.