99 Intrige won't start - acting stange

My 99 intrigue suddenly wouldn't start. It clicked, the dash lights were dim, interior lights were off. I jiggled the key and the lights on the dash went bright and the interior lights came back on but when I turn the key they go dim and there is a click. I removed the key and all the instrument needles jumped.
I can start the car when I boost it. I replaced the battery and cleaned the positive cable connection with a wire brush, hot water and baking soda. It seemed to work for 1/2 day but now it's doing the same thing. Can anyone suggest a fix before I take it to the dealer?

Before this started I noticed that the headlights were dimming momentarily when I put on the brakes or used anything electical like power windows. When I took in the old battery I was told it was dead. I replaced it with a larger one that has 750 cold cranking amps.

Sounds like a classic case of an ignition switch that has gone bad. If you're willing to spend the time, I think it's possible to clean it (there's a guide somewhere around here...), but would be much easier to just replace it.

I replaced my ignition switch a few months ago. It is pretty easy to do as the instructions are great. Just give yourself 2 hours.

Make sure your alternator is working properly. real easy to test start engine turn on AC all the lghts run engine at least 2,000 rpm and take a voltage reading at the battery it should read above 13.5 volts and make sure your headlights are not flikering if they are then the rectifier is burnt-out in your alternator. Do this before you do anything else and it will cost you 0$

After trying to repair the switch on my father in laws car it worked fine for a week. I ended up going to the wrecking yard and got a switch from an 03 Grand Prix and installed it. No problems for about 5 months now.

Back from the dealership. They replaced the bolt and cleaned the positive battery cable connection.

Advise to others: Make sure you clean it well, remove the red plastic!:banghead:

Make sure your alternator is working properly. real easy to test start engine turn on AC all the lghts run engine at least 2,000 rpm and take a voltage reading at the battery it should read above 13.5 volts and make sure your headlights are not flikering if they are then the rectifier is burnt-out in your alternator. Do this before you do anything else and it will cost you 0$

After replacing the battery the lights are not dimming anymore. But I'll find my my voltmeter and try your test.