A strange issue started the other day. 1987 190D Turbo 2,5. It starts and runs fine when cold. Sometimes (not always) when I start it when the engine is hot it feels like one cylinder is not firing at idle. Once I rev it or drive it the miss goes away. Any ideas?

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1987 190DT, clackity clack
90 Mustang track car
95 Lightning

Generally that symptom indicates a dead glow plug.

That would be true if the idle issue was there when then engine was cold. He specifically mentions it runs fine when cold but has a hiccup in the idle when hot. That's not indicative of a glow plug problem. It's more indicative of a problem with fuel delivery and/or compression in that cylinder.

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I had a similar problem turned out to be an injector would leak down. Have you attempted to find out which cylinder it is yet?

Not yet. It does not do it long enough to diagnose it.

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1987 190DT, clackity clack
90 Mustang track car
95 Lightning

Fixed it. I replaces the fuel delivery copper washers again. Cleaned everything and did the correct torque procedure like I did last time. The idle miss is gone. I was sure it was cyl 2 because I could loosen the injector line and it would make the least difference at idle. I did not see any issue with the washer or any trash but it is fixed. It is nailing at idle now but hopefully that should quiet up in a few miles.

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1987 190DT, clackity clack
90 Mustang track car
95 Lightning