terrano 11 airflow meter

You can try cleaning it with pressure pack carby cleaner. Although if you just bought it, it may be covered by warranty if you bought through a dealer.
I have a T2 2.7 TDI & it performs very well. We tow a Track camper trailer all through the Victorian high country, all up weight is around 1100 kgs.

There is a test you can do on the Air Mass Meter that acording to the manual will tell you if it is OK. IIRC it is a voltage measurement between two terminals on the sensor (can't remember which ones though), anyway the test told me mine was OK. I ordered another anyway, fitted it, and could lay rubber as I left the the driveway. Before it was very slugish.
If it is the Bosch one like mine there are 2 ways to clean it. Pull the whole duct out and give it a squirt, or with a star drive security type screwdriver tip, just pull the sensor out of the duct (the better option). Make sure the cleaner has evaporated before putting it together as I am sure it is not good to run the donk on the fumes.

The Bosch sensor has the part No. on the side of the duct, so take it to a Bosch suplier and they should be able to get you a new one for around $400 odd.

Hi bob

I have had the same problem, very common with this car. I now clean the MAFM very carefully with electronic component cleaner, from auto store. I remove the unit an spray it from about 20cm and the move closer, being very carfull not to over stress the 2 fine filiments in the tunnel.

I time my T2 from 1500rpm to 4000rpm in 4th gear, before the first clean this took 45sec after clean it took 23sec, huge improvement, I'd be interested in the results of others doing the same test, on flat ground of course.

the other common fault with T2 is the throttle position sensor on the accel pedal mech. become sticky and un responsive, 1 on know even stuck in the ON position almost causing a collision.

I found this too, it will make finding the bits a little easier when you know what you are looking at.DIY workshop stuff