1999 Toyota Rav4

I had timing belt replaced, 8 month after it broke down. It would jerk and the engine light went on and there was no power when you hit the gas and sometimes would stall. Had replaced timing belt again, was told other one was loose. Its been 3 month now and the truck is during an incline sometimes jerks a little, like what it did before, but not to the extreme. My auto worker can't figure it out.