Really Rough Idle

[luckyone]

1993 240SX Vert 150,000 OEM Miles

The problem began at 147,000 miles,I have a really rough idle. Engine runs smooth at all operating RPM above 900 but with air on or off idle set at 700RPM engine feels like it is hitting on two cylinders when I slow to a stop and foot is on brake pedal. Dealer recently replaced spark plugs but didnt fix the issue. Are there vacumn lines or such that may cause such a problem. At a red light the car feels like it is going to actually stall.

[compactfean]

When is the last time it'd had a FULL tune up? Wires,cap, rotor, air filter, maf cleaning.

[luckyone]

dealer did one at 147,000, at least that is what they reported, they even hooked it up to a diagnostic machine and as usual the car idled perfectly in the garage two days later it was doing it again.

[JDMice]

I'm having the same issue, just this morning a advanced my timing a little with the distributor and now it idles fine. going to replace cap,rotor and wires this weekend and see what happens. If its to high i'll change the distributor back. just replaced my plugs in october last year.

[Cone Killer]

My car did the same thing, idled really rough, but drove smooth. Pulled the codes and had a bad knock sensor, I replaced it, and it idles better, but still wasn't smooth. Found a broken 90 degree formed vacuum line under the EGR valve and replaced that too. All codes were clear on the ECU, all new plugs, wires, cap, rotor etc, etc. Then I went ahead and replaced all the fuel injectors with new ones. Car idles so smooth now can't even feel it running at idle with the AC on or off.

[luckyone]

Thanks for all the help guys.
BTW, I finally identified the culprit, it was a toasted fuel injector, replaced it and baby purrs again