I ditto the injector theory. The slow demise leads them to not "unstick" for longer and longer. Then came the second injector starting to fail. That was a lot rougher idle. If it was as rough as you describe, then I'm guessing you had at least 2 not functioning, because one wasn't too bad for me.
It was / is hard starting when even one decides to wait until some warmth comes, though, even as you stated.

 

Interestingly, I took it to work today and it started and idled rough again this morning. But then after sitting for 9 hours in the parking lot, it was fine when I started it to come home.

Sounds like there could be injector issues in my future ... especially when it gets cold. Is this a "replace the injector" type of deal or can you remove and clean, replace the O-rings, etc. to get more life?

 

Well this is not solved after all. I think it's running better in general after the oil change but still very rough until it gets up to normal operating temp. Tonight I changed the top-end / HPOP oil via the reservoir. I know there is some controversy here about whether that is necessary or not but I figured it was worth a try. I will say this. The oil that came out looked pretty clean, but it was still pretty black, not like the new oil I put in. Guess we'll see tomorrow morning when it cools off.

Any other suggestions on this one?

 

ON start up does it blow smoke when running rough if so does it smooth out when the smoke is gone?

 

Great question. Haven't noticed one way or the other. I will check tomorrow morning. Also, this morning when I started it cold, it was better but still not where it should be. So I wonder if the HPOP oil helped. I also picked up a new fuel filter today and will be installing that later this evening or tomorrow morning. I'll do that and start it cold tomorrow and see if there is smoke.

 

Took it out for a spin tonight. Same behavior. Rough on start and up until it hits normal operating temp. Looked for smoke and didn't see any.

Thinking maybe I should hook up the block heater overnight to see if hot oil makes a difference on cold start?

 

That's a good idea. We all tend to forget about the block heater in summer months and might answer some questions. EOT sensor might be reporting warm all the time. Although they are pretty reliable they have been known to fail. If you have a ohm meter you can measure the resistance with the engine cold. It's a two wire connector on the backside of the HPOP. Unplug it and measure across the sensor. Here a few values you might see ...

0* 250K
10* 192K
32* 92K
50* 59K
70* 33.6K
90* 21.5K
120* 11.2K
170* 4.48K

If it's anywhere close then the sensor is OK.

 

Ran great this AM after being on the heater. But temp was at the bottom of the normal range when I started. Starting to seem more and more like an actual sticking injector. Of course, I don't own a scan tool that can doo a buzz test or CCT. Might have to break down and take it somewhere that does. Probably have to leave it overnight though.

I'll check the EOT as above as well. This forum is great.