89 240sx acting weird at 1/4 throttle.

[meet07]

I just bought this 89 with 211+ miles on it. It runs great but the only problem that im having is:

1) injector #4 keeps leaking. I have replaced the injector 0-ring and gromet. Still leaks.

2) at 1/4 throttle on the belt-line she acts as if she cuts off. I press the gas and nothing happens. After patting the gas about 10 times in 7 seconds it seems like she kicks back in. Literally puts my head back.

3) she also idles rough at a stand still.

I have checked over vacumm lines and replaced a few but I feel that it is something else. Im throwing no codes and sometime when I crank her up she idles high. I was told thats the AIV valve. Pinch the hose and that valve is faughlty.

I just bought this car and dont know much about it except it has morre vacuum lines than my DA integra...lol