Stevooo

Hi people, I have recently had some problems with my 82 hilux and was wondering if anyone could help? Ill get to about 80km-90km and then the car will start slowing down and getting sluggish and then will sit on 60km-70km with my foot to the floor and will sometimes jump. I've ist changed the fuel filter and ran some injector cleaner though it and that didn't seem to do anything, any ideas on what might be happening?