Years ago, when I first became familiar with my beloved 5. 9 cummins, I had a 90 model that idled rough. It ran extremely well above an idle, so I presumed it was an injector. After a little over 350,000 miles, 85,000 or so with a noticed rough idle, I decided it was time to fix my injectors, and the rough idle, as well. I bought a new set of POD injectors, and after installing them, I still had a rough idle. This made me search out W. L. "Pete" Peterson of Decatur, Tx, and my education on Cummins took great leaps in a matter of a few hours. The rough idle ended up being the cam plate in my "tuned" injection pump. A few hours later, it was fixed and ran better than EVER! And I was one happy camper... puller. Just a suggestion, make sure what the problem is before you spend too much money.....