a3144e hall effect sensor

i am working in a project using tiny85 and a3144 to be as a delay 500ms off switch. the programming works fine but when i hook up a mosfet to control a 1a led, the led wont off for 1x seconds. second trigger it decrease to few secs. after few press it seems normal 500ms. but after a rest for around 1 minute it resetted to 16sec, 8 secs, 4,2…500ms.
i had added pull down resister to the mosfet gate.
?????????

Code?
Schematic?