A6000 Downgraded to KK s40 from S58 lollipop(issue over heating)

Hi,
I downgraded Lenovo A6000 from lollipop s58 to s40 kk stock ROM.
flashed using stock recovery with total wipe.It work fine for week,now its show warning CPU over heating and it get restarts,battery also drain rapidly.
suggest stable ROM also as daily driver.
plz need help.

thanks.