+1 on what HWK says,
"Even with small holes most foils will still at least try to fly and inflate fully. Does the kite have dirt outs and if so are they closed? It could be as simple as that." It could be that cross venting inside the kite is off as well.....as in Cell walls have too much air flow. Doubtful but possible.
Did you check your bridle lines as well?, if one two are even stretched a bit you can have out of balance in the equalization on the "intradose" (inside skin of kite) and therefore it doesn't fly well.
If there is a rib, cell wall, or such broken, inside the kite you can check, as the fabric inside the kite is going to have really clean sewn seems unless the kite fabric has been damaged. Then youll see slightly fuzzed out on the edge of the fabric.
I agree that if it is a no name kite, try getting a new one, for likely to be $150-200. It might be $35-80 to have the kite fixed depending on the issue.
Try these guys.....http://fixmykite.com/