td5 2001 not starting after service, ignition harness changed still not starting

so after a service the car was running lumpy , mechanic advised to put in a bottle forte cleaner done that still the same , wondered if it was too low on fuel so put another £50 diesel in got it home it just died, advised on here to change the fuel filter , done that problem solved went a drive round the block just as i was in my street it became lumpy again and died , googled it all and advised to change the ignition harness just done that still not starting the old one had no oil on it

now been advised it could be the crank shaft posoition sensor

any ideas

on my way to get a air bleed none return valve replacment