1984 Nissan 300ZX

Engine Performance problem
1984 Nissan 300ZX 6 cyl Two Wheel Drive Manual 230000 miles

I just replaced my o2 sensor and my fuel pump because i hace been having a sputtering problem and the car has to warm up before driven. I put the new fuel pump in and it worked fine for about three weeks and is still working good. Well yesterday i put the new o2 sensor in because mine completly quit. When i put it in it was smooth for about a mile and now when you push the pedal it just floods and almost kills the engine. Can anyone help me with this problem?
April 28, 2009.

Flow test the cat. Converter(s) to ensure they are not clogged

Apr 29, 2009.