no power to anything

went to start jeep this morning and it had no power. thought it was just the battery so i jumped it. it started up but if i let off the throttle it dies. jumped it again and same thing. took off the cables and again no power no crank nothing. so it only starts if jumped and dies when i let off the throttle. any ideas? '99 sport with about 87000 miles. TIA

It would seem your not putting out anything to the battery. Jump it again and do a voltage check, running it should be 13+ volts. The battery might be flat wasted also.It would be worth while to have it load tested also. I had a similiar situation with a Ranchero. Put a new battery in and it ran for a while till we got home from vegas at least.

ok but the battery being dead wouldnt stop it from running once it is started would it?

yes it would. i tried jumping a friend's xj a few months back. with the cables connected, it would run. if we disconnect the cables, it would cut off. but if we kept the idle up, we could keep it running. the battery was totally dead and held no charge whatso ever. the guy at the parts store tested it and confirmed it. installed a new batt, and all was well

ok thanx. guess ill run to the auto store later and get it check and see if i need a new.