i have a 83 lebaron with a 2.6 liter motor. when it gets to operating temp it starts to hesitates and stumbles BAD when at idle and when I lightly apply the throttle. i have to put it in nuetral and keep the gas pedal accelerated till i have to take off. then it will stumble, buck, and even die. then ill start it right up and itll drive good. whats my first step to diagnose this problem

 

Check for cracked or broken rubber vacuum lines, and then ckeck EGR vale that it is not sticking open.

 

The carb on those old mitsubishi motors were a real pain also along with a relay that had a non existent replacement relay that would go bad and cause the same symptoms, even when they were NEW. I had to work on a few of those motors WAY BACK in the mid eighties, and there was little good info for them then!!!