I'm not convinced this is a mechanical problem (eg related to the IRD). I'm no great expert on the K Series engine, but I think this is more likely to be a fueling or electrical problem. Fueling may be caused by a faulty fuel pump or clogged fuel filter starving the engine of enough fuel. More likely though it is an electrical issue. I understand you have a 2000 car?, if you have a distributor its likely to be the leads (wires) from the distributor to the spark plugs or the coil, maybe something in the distributor (do they have points?) or coil packs.
Does the engine idle smothly? If you are parked up and rev the engine, does it splutter?
Did any lights come on on the dash? If so, I would take it to a Land Rover specialist (there's bound to be one near you) who can plug a diagnostic reader in and tell you what the problem is likely to be.
You say on your profile that you've "Loved landys since a young age" - now you have one, its a great progression in enjoying Landies to then learn a little about how they work. It can not only give you enjoyment, but also help you get the best out if off road whilst not destroying the car and save you good money in the process
You mention in other threads that you want to go off into the wilds camping - then really you should have a basic idea of things - it might just get you out of the pickle one day.
Separate to this issue (or maybe related), as you say you are not very good with cars, have you checked your tyres and VCU are within spec for Freelander? You'll be doing yourself a favour if you read this and do the checks...
https://www.landyzone.co.uk/land-rover/tests-new-freelander-owners-should-do-on-their-car.312863/