1993 Cadillac Deville Starting Problem

Car will not start with ignition key at times; acts like the battery is disconnected. I've replaced the starter and solinoid but problem persists. When the car won't start, I have to wait a few hours then it will start. To avoid this long wait, I put a wire from where the ignition wire hooks to the solinoid. When I touch the hot side of the battery with this wire, it will start everytime. It is real bad to start when it is hot weather here in Alabama. This is when I had to wait several hours to start car with the ignition key before installing hot wire. I've had the ignition chip keys checked by Cadillac dealers; they are good.

When the car won't start with the ignition key, it acts like there is no power from the ignition switch to the starter solinoid.

Please give me an idea of what the problem is. It has myself and many mechanics baffled. I've been starting the car with the wire for 8 years. Any help would be appreciated.