1989 yota pickup

as the title says it wont idle. itll rev to 2500-3000 rpms when i start it, then come back down and die. if i stay on the gas i can keep it running. around 800-1100 rpm it has really rough idle.
It also has no power. i have 38.5 with 5.29 gears it shouldnt be that hard to roll. and if im on the gas when im driving it, it will die down to around 800 rpm and then catch and well be rolling again.
these are things ive changed.
1) mass air flow
2) fuel filter
3) o2 sensor. i never put it back in when i cut the exhaust when we took the motor out. (stupid idea to cut in the first place).
4) i checked all the vacuum lines and i dont hear any leaks.
this is a fresh rebuild. top and bottom.
any ideas what to check next?