Once it gets going it's rough running? Are you sure the Glo Plugs are working? They need to be tested individually by removing the plug in harness at the GP relay and test each to ground. Depending on the meter or cont test you do, they should show somewhere just over 1 ohm or with a continuity test they will show shorted out.
If that's not it, diesels need good compression to start in the cold, the valve adjust is next.

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Doug
'83 300SD "Old Gold" 170,000 mi.
'82 380SL "Green Machine" 190,000 mi.

Some days you're the pigeon, some days you're the statue... I'd rather be the pigeon!