A compression/leakdown test showed air getting past the valves, and I thought it would cure the cold miss ( and smoking). Nope. A compression/leak down test will show how tight the engine is. WARNING: its not an easy job, like on a pushrod V8.

Check all your fuel lines for air bubbles. There should be none. If there are you'll have to isolate the air leak. Common is the pre filter o ring seal. I also changed out the delivery valve seals ( with Viton) as they were leaking. Leaks and diesels are a NO GO.

Lastly, the known cure for my cold start miss - B100!!!!!! It radically mitigates it.

As far as I can tell, I have a piston ring leak ( which I'll confirm with a compression test fdown the road), or an IP rebuild. Neither are required right now, so..