1990 nissan 240sx help!

[ka24depower]

i have a nissan 240sx and i have a header and exhaust on the car.about 2 months ago the car has started idleing weird.the rpms like to jump between 400 and 900 while in park.while its in gear it idles around 500 rpms.when the cars in park and the idle goes up too 900 rpms it makes a whistleing sound.ive replaced the o2censor,plugs,plug wires,cap,rotor button,and injectors.could it be the maf censor or the egr valve.if you can help i would greatly thank you.the car also burns really rich exhuast.

[s13sr20chris]

i would reccomend starting with the basics. check the ign timing, fuel pressure, etc. is the car misfiring at all?

[NISTECH]

The whistle noise may indicate a vaccum leak, see if you can pinpoint the location of the whistle.

[ka24depower]

hey thanks for replying yes i have tools and the tools i dont have i can get my hands on them.i would love to go into more depth on this.now how would i check to see if the car is misfiring.

[Dano]

As Nistech just said, it sounds like a vacuum leak, indicated by the varying idle and the whistling noise. See if you can pinpoint that noise, and its definately not the best thing to use, but its the easiest... use some carbeurator cleaner on the vacuum hose connections you believe could be at fault, if your car's idle makes a drastic change, you found your problem, then fix that leak.

-Dan