2.2 cavalier timing chain again!

have a 97' cavalier,that every since it got about 150,000 miles.i've had nothing but timing chain problems.i replace chain,gears and tensioner(new)everytime but after few thousand miles it starts clattering again.this has happened at least 3 times,this time it must have slipped off.what can make a chain loosen so quickly.haven't took apart this time yet.but in the past i change everything under the cover new,and sounds great for awhile,then starts making noise then just gets louder and louder until i change again.car always runs good though ,even with noisy chain.its a 2.2l

have a 97' cavalier,that every since it got about 150,000 miles.i've had nothing but timing chain problems.i replace chain,gears and tensioner(new)everytime but after few thousand miles it starts clattering again.this has happened at least 3 times,this time it must have slipped off.what can make a chain loosen so quickly.haven't took apart this time yet.but in the past i change everything under the cover new,and sounds great for awhile,then starts making noise then just gets louder and louder until i change again.car always runs good though ,even with noisy chain.its a 2.2l

it's not caused any valave damage when this happens? Have you checked them in case a valve is bent and is causing the camshaft to stick or something like that?!

i don't know if any valve damage this time!this is the first time it came off are broke.kinda worried about that though,but when it happened it just died and i coasted off the road.but something sure is making the chain loosen up in the past.