.3I have a 1999 ford F350 with a 7.3 it has 208,000 miles on it. I bought it about 12,000 miles ago and its been running like a champ till about 207,500 miles, I did not drive my truck for about 3 weeks and now it doesn't run right. When I start in the morning day or night if the motor is cold it runs bad. If I floor it will get up to about 10mph then the turbo kicks in and gets me going to about 25 mph very slow though. Once the running temperature gets up to where it should be it runs flawless. I am thinking this is due to the glow plugs going bad. Is this so? To my knowledge they have never been changed but the truck has been well maintained.

This link, and others under the Diesel Section of the Sticky, may help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-8.html#post1415281

Yes, it could be glow plug-related.

If it pours white smoke when you start it then yes either the glow plugs or the timer is bad. 7.3 I would sure start with the plug timer as they are known for going bad! This could also cause the lack of power when cold because the cylinders are still loaded up with diesel. Kind of like pumping a gas motor too much and flooding it, Doesn't want to run until the unused fuel is gone.