Discovery 2 climbing steep hill off road problem

I was thinking Mabey fuel pump? Or maf sensor

Paul, Thanks for the offer. I am getting in serviced in 2 weeks so I will get them to check it then. Thank you.

I don't think it is the MAF or low transmission fluid because when I came up to the next steep slope (a slightly steeper gradient) I put the car in Low and activated the CDL (the CDL red symbol lit up on the dash saying it was engaged) and the car went up no problem at all. The more I put my foot down on the accelerator, the more power I got and the quicker I got up the hill.