About a year ago (May 2012) my '04 6L turbo diesel F350 Quadcab short box EGR went. It vapor locked while I was towing my 5th Wheel and was so bad I ended up having to replace the engine with a used '04 (110,000km) engine and put a EGR delete in. I used it over the summer (2012) for short trips and to tow my trailer (28ft 5th wheel) maybe three times on short trips - around 300km. The fall of 2012 it began to start with difficulty when it was getting cold outside. It started when I plugged it in but if it sat for more than a few hours in the cold weather (not extremely cold - just freezing) it would not start. They replaced the batteries and it still did it. It turns out it was the coils. They replaced the coils and it started fine. This winter/spring (March 2013) an injector died and another was operating at about 60%. I had them replace ALL the injectors with new Ford injectors. After the injectors were replaced I drove it maybe a half dozen times around town and on a couple of trips to town (300km round trip). On one of the longer trips in mid May 2013 I was driving home and it started missing. At first I wasn't sure I even felt it. Then it started so bad it was shaking the whole truck. It would then smooth out... and start again. I took it into the shop thinking I may have got bad diesel and had them do the fuel filter (which wasn't really bad but needed changing). It did not do the trick. Since then they have replaced the cam and crank sensors twice, the FICM (and reprogrammed the ficm, ecu, bcm), checked all the wiring harnesses and wiring to the ECU, bypassed the catalytic converter, performed cyl contribution test - passed, drove the truck with scanner hooked up - no injectors dropping out even when truck is 'jerking'. No codes and it is passing all the tests. Replaced the turbo with a known working one. The latest is they have replaced the injectors for a second time and replaced the ficm. Still doing it! It starts great every time and will run great until the engine warms up and it will start doing it. More when applying gas but it will also do it while idling. It sometimes does it a lot or a little and smooth out for a bit and then start again. It has been in the shop for 3 months and we can't find the problem... help!!