Misfire?

 

Idle surges up, engine shakes, rattles then back to below idle, sometimes stalls but only when cold. I’ve been rebuilding vintage cars, 50-70s for over 50 years. These damn computer cars are a pain! Because there was no change in idle surges when I unplugged maf sensor I logically determined it was the maf sensor or cable. I changed both with no effect!

 

Are you able to read fuel trims ? Sounds like trims or AF ratio is going bonkers.