2.0tdi mis fire

Good morning clever people.

On my drive into work today I noticed the glow plug warning light began to flash, No loss of power or and strange noises or vibration.

Pulled over after 3 miles to check as that was the next safe place to do so. Noting visable or leaking. When I restarted the engine no flashing light.

It was fine for about another 15 miles, Went to pull away at a roundabout and it sounded like a slight backfire followed by flashing glow plug light again.  This time clearly power loss(limp mode).

Pulled over once more to check nothing loose or obvious. Only had half a mile to get to work so set off again. This time flashing light and power loss again but no juggering or funny noises when this happened.

Not long had the car and was completly full when I got it.

It's now down to 1/4 tank so maybe I was thinking injector fault if something ad been sucked up.

Car has done 74k but over the last 4 years it's only been averaging between 1000-2250 miles a year.

It has been feeling better and getting smoother all the time i've been driving iy(only 2 weeks i Know)

Wanted to fill up with some vpower diesel and give it a good clean through.

Any ideas or suggestions greatly appreciated.

Oil shaft has been replaced and it has a full service history fron Audi.

Last serviced 8 months ago(900 miles)

Thank you in advance