Higher the cetane number better is the diesel quality.
Cetane is for diesel what octane is for Gas. Higher those number better is the quality.

If the car had been sitting with fuel in it for too long, I have heard from people, that engine acts wierd during idle dont quote me on that I have just heard this from a truck guy once. Just to be on the safer side get the old fuel out and put the fresh one in. Also try one of the quality diesel additive in it. This way you get the bad fuel theory out of your mind while troubleshooting. Timing chain suggestion is good.
Welcome to our little family.

MVK

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One penny saved is three penny earned.

1985 300D Turbo 179,000miles