Running problem 1.9 tdi estate

[quest63]

So finally finally I managed to get the new suspension fitted on my car. Well when I say I that just means I managed to find an afternoon I could do without the car and someone to slot me in and fit it for me. Feels good so far (somethings still creaking but it can wait)

So I still have this running problem I mentioned previously. and I'm looking for maybe some simple things I can check myself?

To start with theres no engine management or other lights present.

Prior to this problem the car maybe went into limp mode 18 months ago briefly when I was taking a mechanic advice and doing 60mph in third gear up the motorway to potentially clean the cat.

The problem started over a year ago at 30mph in 4th gear. Previously if I took my foot of the gas at this speed the car just kept going along and didn't slow down pedal didn't feel like it was sticking or anything but the car just kept going happily at 30mph.Maybe not in all circumstances but some!

Then at some point this must have stopped and I now noticed at 30mph in 4th it was getting a little stuttery at this speed. The problem doesnt show if you say accelerate away from standing on the way to 50 or 60 mph or at least its not noticeable. Just if you want to cruise at 30 in 4th.

Then I noticed after 12 months or more of this a similar stutteryness has developed in 1st and 2nd when pottering in traffic at a set slow speed but it goes away or is un noticeable if you accelerate.

I'm not 100% sure but I think its less noticeable when car cold ie. on choke and maybe a little less bad when theres more fuel in.

Awhile back I had the fuel filter and air filter changed and gave Forte diesel cleaner a one off go but no difference.

What simple, and I mean simple things can I Check myself please?

Thank You