It could be a number of things.
1) Check the air filter. If it's blocked the engine will struggle to breathe and you should see lots of black smoke when you put your foot down.
2) Fuel restriction - try loosening your fuel cap. There's a little vent hole in that which is supposed to allow air back into the tank as the fuel is used. If that's blocked, your fuel pump will struggle to get the fuel out of the tank.
3) Dirty injector(s). Run some injector cleaner through it. It might take a while to clear up, the alternative is to pop them out and get them professionally cleaned.
4) Fuel filter blocked - basically you need to replace it to determine if that was the problem.
There might be issues with neutral position switch or the crank angle sensor. Your CAT might be blocked, causing the exhaust to choke up. I suppose your turbocharger bearings could be on the way out and the turbo isn't spooling up well - check that one out really soon. Take off the intake hose and give the turbo a wobble and a spin. If it wobbles that's bad news. It should spin very smoothly and freely. If not, that could be your culprit.
Hope that helps.
