1994 Ford Escort ignition switch / starter problem

I'm stuck, guys! I think the problem lies with the ignition switch itself (when I bought the car, used, a few months ago I realized I could take the key out while driving down the road) but i'm not sure how to go around it.

i've already installed a push-button starter to bypass the "start" position on the key ignition but, after working like that for a few days, it quit working with the key in the "run" position. The solenoid will click -sometimes- and all the dash lights and interior noise functions are dim, shaky, and sporadic at best.

i took a voltmeter to the battery - it's fine - and voltmeter readings to the push-button starter read fine. However when I push the button in the reading drops to 2V to 4V.

odd thing yesterday: I let the car sit for a day in my shop, put a different battery in it, and it started fine the first time. Shut it off and waited a bit, after that it wouldn't start at all.

any help would be great. I'm thinking of maybe putting a toggle switch in to bypass the "run" position but I have no idea what wire it is.

thanks!