Help with misfire type issue 2004 1.9d.

[Neilh1234]

There is some beer money in it for anyone who can help with this!

Its my first post . Ive been looking for the right place to ask . Hopefully this will be it!

I have had a s40 1.9d (early model - ie 2004) for about 9 months. I recentlyt made the stupid mistake of putting petrol in it by mistake and running it oblivious for quite a few miles until it would no longer fire up. I know, Im an idiot! I think i must have got mixed up between mine and my wifes car and been on autopilot at the forecourt)

I got it flushed and new filters etc. All seemed fine.

However Ive started getting a misfire (if you can indeed get them on diesels that is). It only happens with the following conditions however:

Engine warm (after a good motorway drive)
I stop at a set of lights or at the entrance to a roundabout for approx 30 seconds and have my car idling for this time.
Then when i set off the car sort of misfires quite violently pulling me back and cutting out the power intermittently basically making it very tough to accelerate when its needed. It often goes on for 20/30 seconds only and sometimes can be stopped by moving up to a higher gear. things will get back to normal after 30 seconds and drive fine.

I had the car on diagnostics and only error code related to MAF. I have had MAF replaced a few days ago. Problem still happens however.

The garage thinks it must be an injector problem but apparently this is mega costly to sort and given the age and mileage of the car I dont know whether it would be cost effective to try and resolve.

While out giving it some beans earlier with forte diesel treatment added I replicated the usual misfiring scenario a few times and sure enough it would do it after accelerating following some idling when hot. I did however find that if I keep the revs going while my car is stationary (ie 1500rpm) it will pull away fine with out any misfire.

Ive searched and searched for similar problems but to no avail. Anyone on here with any pearls of wisdom?

I cant really afford a new car right now or to get the injectors analysed.

Thank you.