passat 1.8 20v hesitation at low revs

[tonsofun]

I have been to look at a 1998 1.8 20v passat (non turbo), all seems very good, solid car, however there is a hesitation below 2,000rpm, just losses power, if you put your foot down it doesnt accelerate hardly at all untill it get above, then seems to go ok, any ideas what this could be?

Cheers
Mark