I have a 96 7.3 powerstroke. 300k miles. I was at the store the other day, idling the truck and it started missing and smoking like crazy. It feels like it is missing on one cylinder. Someone told me when they switch to summer fuel to winter blend it may cause an injector problem.

From what I am guessing, I think I have an injector sticking open. Down the highway at about 2k rpms it runs great. Slow down and drop the rpms under 2 k and it starts smoking again. By idle it is smoking pretty strong.

Anything to try??? Does it sound like an injector? If so any easy way to tell which one??