This engine is a N-14 redtop in a 98 Pete. It skips at an idle but only after the engine gets up to operating temperature. It will not show any codes or act differently during an injector cutout test. It has been worked on and repairs made several times but the skip persists.
I had one that did that fuel lines from the tanks to engine were coming apart inside. Plugged the check valve up in fuel line with rubber pieces. Also had a lot of slime in the tanks took them off and cleaned them and replaced fuel lines. Solved the problem of the skip in my n-14. At least worth checking. This new biodiesel is not friendly to rubber fuel lines.
The N14 great engines, when it is missing you can disconect the wiring plug on the rocker box, to find the miss, one at a time, it will not bring up a code. Shut it down, then if you test the wiring to the injector with an ohm meter .5 to 1.5 is normal, If it is open circuit, remove the pass thru conector, and take a pick and put it behind the plug conector from the injector then disconect it and check the resistance, many times if it is heat related it is the Pass thru conector, you buy them with the "O" ring cheaper than the pass thru and the "O" ring seperate. I use synthetic gear oil to install the pass threw. I have the wiring on the injector I removed from a faulty unit, I use that to test the conections on the outside, You also get a free plug if the clip is broken on one. Just a thought!
Could be an indication of a failing ECM. The Redtop in my 99' Binder would idle dead smooth cold then after it warmed up it would randomly skip. Over about a year it started getting worse until it would start doing it during a hard pull and not clear up until I shut it down for 15-30 minutes. Started throwing random injector codes the last couple of months. Changed every injector, all the pass throughs, and wiring and it was still there. Finally had a specialist test the ECM in an oven and sure enough it was losing injector drivers when it got hot.