Heres the deal. Got a 2003 lancer es. 2.0l sohc. got 300 thousand highway kms on it. recently changed timing belt at a dealership. now when driving the car it seams to flutter or bog out when on gas pedel. kinda makes a farting noise out the muffler. if i let off the gas and then hit it again it stops for a bit but comes back. it seams to be wayyy harder on gas too. changed plugs nothing. anyideas plz

 

If it did not do it before the dealer changed the belt and it started doing it right afterwards, go back to the dealer, hopefully you can convince them it is their issue. Sounds lke a timimg issue from what you are writing. Could be a coincidence that something else is wrong...that does happen to me.