Crappy gas mileage/Dipping Idle

[justjuiceit]

I got my 1993 240SX in April and I was amazed with getting over 30 mpg (with 87 octane) with mainly highway, but some city driving too. Recently the mileage has been in the lower 20s. I changed the oil, air filter, sparkplugs(NGK) and the wires in hopes this would help, but it didnt. One thing I did notice when my gas mileage started getting bad was when I came to a stop with the clutch engaged(shifter in neutral), the rpms would dip below 500 rpms, then go up to about 600. Sometimes I would tap the gas so it would idle at 700 rpms. With the a/c on it didnt dip the rpms at all, but recently it has been dipping to about 700 rpms with the a/c on while it usually idles at 1000 rpms. I probably should check the engine for codes, but the check engine light burned out, is there an easy fix for that? Any ideas for what the problem may be? Thanks for any help.

[s13sr20chris]

check engine bulb is an easy fix. remove the gauge cluster and take apart. bulb is cheap. i will just mention the typical stuff to you for poor idle. check for intake leaks, poor connections(maf, ect, etc.), poor grounds at maf, and adjust idle/timing/tps. it sounds like bumping up your idle may help.