Air in return diesel pipe 1.5 dci

Hi

2004 1.5 dci scenic 2

Bought as non runner cambelt snapped

All now running but......

Car starts first time from cold or warm

Will tick over just fine

Take it for a run and temp fine, acceleration fine but every now and again injection fault and stop light flashes and then goes out.

Cleared all historic codes and P0089 is displayed once and nothing else despite perhaps 6 flashes over 15 mile run. If nothing was displayed, you wouldn't know something had happened.

Look at clear fuel pipes going into and out of pump, solid fuel into pump, return shows a consistent 1 inch air bubble and very irregular burst of fine bubbles.

Replaced metal pipes from distribution point plus pump pipe. Replaced fuel filter. Replaced copper injector washers, glow plugs were renewed before I purchased car. Car has had cambelt, tensioner, water pump, aux belt, battery, oils, secondhand cylinder head, gasket set, bolts, lot!

I'm assuming the air bubbles are causing some sort of misfire as a guess

But help, anyone seen this before or got clues where to look from her Eyes?

Help!