I have a 1980 Civic 1300 with 5 speed. I do not really know the mileage on it, my guess is 300k.

The problem I am having is that it falls on its face at half throttle. It has a new distributor; on the old one the vacuum advance plate was toast.

So I don't know why it is doing this. Any help is appreciated.

 

It misfires, or it just won't go fast even though it runs smooth?

Misfiring at heavy throttle and low rpm is usually weak sparks.

Running smooth but not fast could be because the cam is out of time.