ka wont start

[slide240ss]

So i went to home depot the other day and when i got back in to leave, it ran rough. i knew right away it was an injector because i took the plug off the second injector and nothing changed. drove it home, went and bought a new injector, put it in and now it wont start. but, when i first put it in, it ran.....SUPER rough for only like 3 seconds with the throttle mashed down and thick white smoke billowed out the exhaust that smell like gas.

and by the way, it ran perfect before this happened.

I AM STUMPED!!!!!!

any input would greatly appreciated. thanks

[GO240]

... um possibly a vacuum leak get some sea foam cleaner and run it through your brake booster vacuum and see if smoke comes out anywhere besides the exhaust and try to get a 300zx fuel filter and put it in