1998 Kia Sportage OBD code P0264

I am working on a 1998 Kia Sportage it runs like it is only hitting on 3 cylinders and lots of white smoke. I did a compression check all holes good compression so I replaced the plugs while I had them out, I put a OBD scanner on it (check engine light is on) it had multiple codes P0264, P0300, P0302, and P0301 so I put a set of injectors in it and it ran good no smoke and ran smooth that lasted for about a day then back to smoking and running ruff. It is running better since the new plugs and injectors but not the way it should. I put a long screw driver on each injector and you can hear #1,#3 and #4 clicking but not #2 it appears that #2 injector is staying open all the time as it is running you can smell the raw gas and it is dripping out of every joint in the exhaust system it is not leaking when the engine is off no gas in the oil or is it hydro locking the engine. I think the code #P0264 (cylinder 2 injector circuit is low) is my problem. Can anyone point me in the right direction so I can get this Sportage back on the road.

Thanks

Well you need clear that #2 injector driver problem. 1st read voltage fed to that injector: here is the circuit:
www.geocities.com/lmp4203/kiasport/injectordrivers.jpg

Disconnect plug to injector #2 and read voltage: on one wire with key ON, you have 12V. On the other wire, white green stripe ,you have "undertermined voltage"...that is, is is supposed to be an open circuit anf the computer driver connects that wire to GROUND only when injection is required. A RESISTANCE check to ground should read infinite ohms..or a very high resistance. If it shows low resistance to ground of that 2nd wire (key ON or OFF) ...like a few ohms, then the driver is shorted (injector circuit LOW) and this is the problem. I have not investigated this driver: can be a removable discrete transistor that then can be replaced, or a transistor bank (several together), a little more complicated....or imbedded and epoxy sealed in the PCM...bad news. You can have a wire shorted to ground too....
Come back with results for that test.