defender problem - lose of power

Hi was wondering if anyone could suggest why my 2005 td5 defender with 33000 miles and full service history has started to loose power when I try and accelerate from 35ish up. When this happens I am lucky if I can get 25mph. I did notice a high pitched whirring noise coming from the engine compartment a few days ago when I switched off. it had a new fuel pump fitted about 6 months ago. any suggestions wouold be greatly received by this landy virgin

I'm no mechanic but clogged fuel filter maybe?

Cheers for that will have it checked!

One usual suspect (and dead simple to check) is the MAF sensor (immediately downstream of the airbox). Simply unplug the electrical connector from the MAF and go for a drive. With the MAF disconnected the ECU will choose default settings; if she now goes like snot off a stick you've found the culprit.

service it

your whirring noise could be your oil spinner slowing but not usually high pitched, check turbo/intercooler hoses and around manifold for air leaks

thyanks to all those whio replied