Dodge Ram 1500 truck acting goofy

My 1997 Dodge Ram 1500 4WD extended cab is acting goofy. First--and this is a continuing problem--it doesn't like to start. It has plenty of battery, but I have to jiggle the shift lever from Park to Neutral and back again, and finally it works. I get power to the starter, and it starts just fine. Once it starts, it will start again and again, no problem. Until the next day.

At the exact same instant this problem started, it suddenly refused to idle. Let off the gas, and it just flat died. Went from 1500 rpm to zip, and died. It was like turning the key off.

So I had my buddy come over with his computer to check the engine codes. Alas, I made the mistake of telling Mr 10 Mpg* (the truck) that my buddy was coming over, so--after I got it started--it decided to idle, like normal. The check engine light went out (it is usually on all the time because of a bad rear O2 sensor). When we scanned the codes, nothing came up. This is a classic case of Murphy's Law of Mechanics.

However, the ABS and Brake lights came on when my buddy was scanning, and now they stay on all the time. Truck stops fine, but the ABS/brake lights stay on.

Sounds to me that everything is related, but we can't figure out what it might be. Ideas, anyone?

*It gets 10mpg whilst towing the race car. Around town, 17 or so.