Idling and possibly running rich Options

[sugarfree]

I'm working on a beams motor. It's been installed and starts up, but i have a check engine light. The check engine light does not come on right away, it takes a while to come on. I'll let the car heat up to normal operating temp and a little after the check engine light will come on. Or if i turn off the car, and restart it does the same thing, the engine light takes a while to come on. I idle at 1100 or 1000.

The previous owner had plugs in there that were black, and i haven't checked mine bc I've replaced them, but I'm thinking it's still running rich. I can't use the ob2 port to check for codes because it doesn't work.

I've been recommended to clean my maf.

Would it be possible the previous owner messed with the timing?

Any suggestions?