What makes your dealer so sure its the AFM ? have they done a diagnostic to prove it ..first thing I would be looking at is the crank sensor because this is classic symptoms of bad starting on many cars with electronics on board..

Crank sensors are usually situated at the crank pulley and take a signal from a toothed ring here to find crank position..



This isnt a palio but is typical of what you should find down there..

The crank sensor should also throw up a code as will most electronic faults..but saying that quite recently my sons car had a crank sensor fault [bad starting] and no code or engine light came up on his car..his sensor was covered in oil from an oil leak and once cleaned and leak sorted its starting first time again..might be worth giving the sensor a clean and the toothed ring as well and check the gap between the both..some time if the gap is two large between them then it can cause a signal/comunication problem..also there would be no harm done if you took out the sensor from the AFM and gave that a clean as well with contact cleaner..I take it you have checked other things like plugs and coils etc..mechanical problems are hard to diagnose online but you might want to look for things like air leaks between the manifolds and head this can cause intermittent starting problems as well..other than this I dont know what else to suggest..