The truck in my signiture will surge at idle. Also when driving when I pull up to a stop sign or red light it will go below idle then back up, it will do that a couple times and then get to normal idle. There is no codes come up,new fuel filter and new FCA. The lift pump is new, bd diesel kit. When I changed the FAC it was good for 2 weeks thought I had found the problem then on friday it started to act up again. I even noticed it takes a second or two longer to start. I have basic tools nothing to get the fuel pressures.