Engine Performance problem
1998 Toyota Rav4 4 cyl Four Wheel Drive Manual 110k miles

I had the timin belt replaced by a mechanic. The engine runs smoothly but it lacks power the way it used to be. It also lacks the acceleration as before. Further, the engine seem to suck more air from the air filter as it makes a loud sucking sound when it accelerates.

Do you think it has something to do with the timing? My mechanic iinsisted that the timing is not the problem.

Please help.