I have a 2003 Durango slt plus and the shift lever is stuck in park. It wont go into another gear at all when running or when the key is in the run position.

 

Possibly a bad brake switch.

 

what he said ^

you can test this by unplugging the brake switch and see if it will go into gear (dont drive this way as you will not have brake lights :O)

 

I unplugged it, and it shifted, so I put it back in and tried again and it shifts again. I must have had a loose connection but I am going to replace the switch.

 

If the set up is similar to the Rams of the same year, there is a little lever in the column by the shifter that sticks. My '03 did that. It would sometimes be difficult then got to where it wouldn't unlock at all. Get some WD-40 gel lubricant. Pull the rubber grommet next to the shift lever open and look inside. You'll see an aluminum arm in there. That's your lock. When you turn the key on and step on the brake, the little tooth on the bar should release. If it sticks, it won't. So, just a little gel lubricant and it should work fine. If not, your brake light switch or neutral safety switch is bad. I'd go the cheap and easy fix first. If it works, great. If not, you're not out much. Just a sort shot, don't soak the column inside.