I have a 2003 3500 5 speed and I am in desperate need of some help. I am getting codes 0121 & 0122. I replaced the throttle position sensor and it did not fix the problem. The dealership then said I needed a new ECM, so that was replaced. The truck worked fine for about 2 weeks and started the same problem again. I parked the truck for about 25 days without running. When I used the truck again, it worked fine for about 3 days then started acting up again. It acts like it's missing and not getting fuel. When its working properly, I have plenty of power therefore, my thoughts are it is still an electrical problem. Any advise on what to check next is greatly appreciated.