force close / disable the most suspected apps, then to see whether advert still on going,
you may not try 1 by 1, may be 3 by 3, to save your time.
once found the defected apps, uninstall it.

when advert pop out, check your current 'running' apps, then you can limit down the qty of apps to check.
let say you currently have 5 apps open, advert pop out, then these 5 apps could be defected, check 1 by 1 , it may not only 1 defected, may be more than 1.