power loss or lugging help

[krittrkeepr]

I have 98 zx2 that is having engine lugging problems when it gets to 1/2 tank or below. The check engine light will sometimes come on and the code said it was o2 sensor too rich or lean.
The car also experiences a loss of power when put through harder acceleration hitting about 4,000 rpms.
The above issues have been going on for a bit but the car just recently has also developed a rough idle and sometimes will turn off.

I have replaced the fuel filter, plugs and wires after these issues cropped up.

I am going to have the injectors cleaned at a shop.

I am wondering if this isnt a fuel pump issue but if so why the half tank issue and rough idle??

Anyone have any ideas??

[Markb873]

The first think that popped into mind is that below 1/2 tank your reaching a hole near the fuel pump and it's sucking in air. Like when you crack a straw at Applebee's and it get harder to suck pop up. Hook a fuel pressure guage up to the fuel rail, tape it to the window, and monitor the fuel pressure, if the fuel pressure is low and the filter was changed then check the fuel pump. The fuel injector cleaning is a waste of money, if the car runs good at some point then the fuel injectors don't need cleaning. The rough idle would be caused by air bubbles in the fuel system. Not enough fuel getting to the motor.

-Mark