Odd question but I brought my 2003 7.3 to local mechanic to get the glow plugs replaced as it was hard to start if below 60 deg F her in Northern Mn. Changed those as well as the gasket covers. Picked up a week after and right away the engine light is on and it ran rough without much power. Now, just to give some background, I did purchase the truck a year ago with everything noted in my sig except for the van turbo. I bought that, had it refurbished, and installed back in February of this year. No issues at all until I had this work done. Mechanic indicated that the codes were in regard to 1. No intake air temp 2. exhaust back pressure flap (no signal) 3. codes present in injector driver module. Couldn't tell me exactly what those codes were. Also indicated that the computer is seeing -40 deg temp when it's trying to start. Also, I took out the programmer so it was operating on stock mode, but that didn't change anything. Also, when it was 45+ degrees out earlier this past week, it was hard to start, almost the same condition as before I had the glow plugs installed. Anyway, i brought the truck to another mechanic whom has more knowledge and equipment in regard to the programming and he said he's never heard of this issue occurring and said that if he can't fix it, then he suggests putting the stock turbo back in. Based on common knowledge of the operating condition prior to this occurring, the van turbo swap would have nothing to do with this....Any assistance would be very much appreciated and my apologies for such a long write-up.