Starts but won’t run issue, help me trouble shoot

So I drove my car (65 New Yorker) to get breakfast this morning and everything was fine. I got back and washed it, then when I went to put it back in the garage she would start like normal, then immediately cut off when I let off of the key/put it in the run position. I tried it a few times and figured out that she will run if I hold the key just off of starter engagement. Obviously not good, but I was able to back it in the garage and she ran fine while doing so. I've never had a similar...

Starts but won't run issue, help me trouble shoot
Author: BigblueC