First off im new here so any advice would help out greatly. I have a 2001 TJ 4.0. A few months ago i was driving home from work and the jeep started sputtering and back firing the code came up for missed firing and so i replaced the plugs and coil pack. After i completed the job took the jeep out to see if that fixed my problem but it did not. Jeep started throwing new codes for cam shaft sensor and crank shaft sensor so i replaced both of those. Now jeep runs and idles fine no issues when on flat ground. When i start to go up hills jeep starts sputtering wont go over 2k rpm and will stall out. And the only code it gives is the P1391. Is it possible i need a new timing chain? Any help on this matter will be greatly appreciated. Thank you and sorry this is so long.