I took a gamble and bought a 7.3 with 100k on it but it would lope at start cold or warm if you Rev ed it up for a second it would even out though. The truck had only put like a couple thousand miles on it in the last 4 years and I did sit in a garage those years. When I bought It I did notice the truck had a small fuel leak by the fuel bowl so I resealed and cleaned the bowl. Before this I also ran 2 tanks through it with hotshot diesel additive and the lope went away for a couple days. Then I flipped to the back tank which still had diesel in it from who knows how long ago and it started to lope at start up again. I ran a couple tanks through the other tank. The lope actually got alot better and did rev as high at lope. I changed to synthetic t6 oil and the truck ran alot better but still loped. I resealed the fuel bowl after all of this and the lop stopped for a while. But then it came back and I noticed that I messed up the oring on the bottom of the fpr. So I ordered a new ring and diesel drips out of the fpr until I get the oring. My question is what could this be injectors? Hpop? Bad diesel? Dirty tanks? Fuel leak I am still waiting for the oring. Also the truck was in Florida until 2008 I ran the farfax to make sure. I really need help.

 

Change the fuel filter to see if that helps. If it doesn't my guess is an ICP or IPR

 

Try starting the truck in neutral. If it starts without loping then you need to replace the neutral safety switch mounted on the side of the transmission.