Well, bad glow plugs will set a code plus when you start it it will smoke white smoke that smells like mosquito killer. It will be very strong. If it does not smoke but behaves like a car with a bad carburetor i.e. a rolling start where you have to hold the key on longer then normal once it starts to catch that could be a bad FICM. Do you have a set of digital gauges like the edge insight or scan gauge II? They would tell you or at least suggest what is going on. Are your fuel filters still good, meaning are they less the 15k miles old? Does it seem like it is spinning at the normal rate of speed?
Member # 23075 Reged: 07/18/02
2005 Excursion w/ 6.0L PSD - Edge Insight, RCD EGR delete, Turbo Drain/Turbo Feed/Blue Spring/Oil Cooler Updates, Dfuser Coolant Filter, 240amp alt, fumoto.
2008 FX4 F250 CCSB w/ 6.4L PSD - Edge Insight, H13 Bi-HIDs, custom coolant filter, "all deleted", fumoto.