i would definitely recommend watching some of the top falcos play. even from melee (since falco hasnt really changed). It wont take you long to figure out what youre doing wrong if you just watch how their falcos carry from neutral > combo > kill. If youre having trouble killing with falco, youre probably doing it wrong, so all it might take is a bit of an adjustment to snap into gear. even against yoshi, you should have no problem comboing him pretty hard and getting a solid dair spike or fsmash to finish him.
In fact,
http://www.youtube.com/watch?v=tekmOPW73hA. this is specifically the MU youre talking about. maybe you can grab some insight from this. Notice that the falco does struggle against the yoshi, however, it doesnt take much effort at all for him to even the stocks out. once you get to the 4th match, you can see that the falco really started to get comfortable, and shut down the yoshi pretty cleanly. granted this is melee, but still its a pretty good starting point. Im sure there PM videos you can find too of this MU
