first use a multimeter to diagnose injector failure. you can be fairly certain that it is injector failure since the 1.6s are very very very prone to it, and it almost always happens on cylinder 1, but i would still check to make sure.
to measure the resistance of the injectors, disconnect the injector wiring hanress connector. this is at the right hand side of the fuel rail when looking in engine bay. inside the connector there are 5 pins. the centre pin is the earth. touch the black terminal of the multimeter on this pin. the other 4 pins are each for an injector. touch the red terminal of the multimeter on each of these pins, making a note of the resistance for each pin.
each injector should have a resistance between 14.5-15ohms. if any are lower than 13ohms i would replace them.
if you search for posts by me (jug) and search for 'injector' you should find plenty to help you out. you should also find instructions detailing how to change the injector. its very easy.
a scrapyard injector will only cost you a small amount (i usually pay £5 for 1 injector)
make sure you get the correct injector, there are two types- 4hole and 2hole. the best way to make sure you get the correct one is to remove it from an engine exactly like yours. there are 2 different inlet manifolds on top of the 1.6 engines, metal ones on the earlier models and black plastic ones on the later models. you will have metal or plastic so simply make sure its the same on the car you remove them from.