I bought the jeep used in August '10 and found out how to do a self-diagnostic check with the key switches in the ignition. I received the code 12 42 21. Immediately afterward I tried to start the jeep and it would barely start. I had to keep the rpms at a minimum of 2500 or it would die on me. After letting it die a couple times it started acting normally again.
Since then it's done it a couple more times to me. But after a couple times dying it starts acting normally again. (Not in cold weather.)
In the middle of December I took it to the shop to get new tires, brakes inspected (the ABS light has been on since I bought it), and an alignment.
The day after bringing it home, I jumped in, unlocked the doors from the inside, and went to start it, and it died. I took the key out, put it back in, and immediately all the power went out. I took the key out, power came back on. Put the key back in, power out. I got out, shut the door, waited for a minute or so and got back in. It started up like nothing was wrong. It's really frustrating - the shop has no idea what it is, and I really don't want to get stuck somewhere in the snowy mountains of PA this winter.
Any ideas? Thank you so much in advance.