2002 Escort Van 1.8 Diesel (non Turbo) Engine Issue

Hi There

Have a 2002 Escort 1.8 diesel van with 101,000 miles (work horse) just lately its become ill

Last week its was driving perfectly until all of a sudden it started knocking & smoking

It has had timing belts along with water pump changed recently by myself ( ex ford mechanic ) & a full engine service & she was on the button as always

• I have re-checked the timing both on the cam & the pump - Timing is perfect.
• Removed the cam cover & checked the cam & followers - All ok & doing what they should do.
• Cracked the fuel pipes coming from the pump to each injector whilst it was running and it went to cut out on every cylinder each time - Also swapped out the injectors one by one with a known good injector - Still running rough.
• The engine sounds and looks like its off a cylinder at idle - It knocks & smokes (blue smoke) between idle & 3 thousand revs after 3 thousand revs it sounds & performs normal.
• It drives OK and still has the same power as it ised to.

Going to remove the injectors again and perform a compression test on each cylinder to eliminate a bad valve or broken ring(s)

Head gasket OK & strats straight away

Could the avanced solenoid on the pump be faulty ?

Cranking note has changed slightly (timing ok though) & it's putin up through the inlet manifold on idle

Any ideas guys ?