New guy needing some help, no power 86 305 SWB

[69long bed]

Hi guys, I just picked up a 86 SWB. It apperes to be all stock 305 TBI with smog. I have two differant things going on, Idel goes up and down, and has a major loss of power.And it seems to be using a lot of gas

Any ideas of what to look at or for first?
I have checked for lose wires and vacume leaks, plugs wires all look good.
When its running good it has great acceleration and kick down/passing gear works. When running bad it has no power or acceleration and no kick down or passing gear.

It still has the catalytic converter and all smog equipment.

Thanks in advanvce.