Sportrak sluggish


I have a 1992 sportrak which i purchased some 4 weeks ago,it has gone through an mot with no probs but is very sluggish when driving, revs fine out of gear but struggles when driving,also the fuel economy varies between 20 and 25 to the gallon but nearer 20.
The vehicle also pinks i have adjusted the timing but if you retard it as far as to stop the pinking you top out at 50mph,any help would be much appreciated, Phil [scimitar]