Dazed and Confused. Please Help

[nightshift]

2 day ago I got out of the my 240 2 do something and left it on and all of a sudden the idle went from its nice usual hum at 900 rpm to just plain nasty it was bouncing between almost 0 and 2k rpms . . . so I went home changed the sparkplugs and sprayed some carb cleaner into the throttle body and it ran like a champ and everytime I let go of the gas it pegged 900 without fail. Tonight I decided to go driving around and all of a sudden when I put the car in neutral and took my foot off the gas the car just cut off, the needle just dove no bounce nothing just straight down and the car cut off. I turned it back on and it ran fine? It actually feels kinda powerful tonight. Took my foot off and it did it again. This was like 4 times. So I decided to go home and when I hit this mile straight stretch of road I just floored it and when I hit the brakes at the end the car didnt cut off and it pegged 900 on the RPM Gauge perfect again, didnt have any problems the rest of the way. Got home and let it idle and after about 4 minutes it did it again. Any ideas?

[240canuck]

check your throttle position sensor sounds liek it could be troubling you. there is a procedure to test it in the FAQ section of 240sx.org

[nightshift]

well the TPS is about 3 months new, of course ill still check it cause you cant rule anything out, but any other suggestions?

[240canuck]

i'm gonna sound like a broken record but CHECK ALL THE VACUUM HOSES its crazy how vacuum is what keeps your engine running sometimes. and this suggestion is comign from left field but (I used to have nitro model cars and my 2 stroke engines with carbs used to do that alot due to flooding of the engine or an overly rich mixture0 so maybe its running too rich. now its computer controlled fuel mixture so maybe your air flow sensor is messed or your injectors are cracked and allowing too much fuel in. thats a little bit of a crazy suggestion but give them a once over.

[Nismo_Freak]

Too check fueling... pull plugs 1 & 2 ... look at them. They should be a light brown color. If white... your running lean... if black your running rich.

[nightshift]

Well when I replaced the plugs they were light brown but the top of the outer part were the tread is was black.

As far as today, I put some fuel injector cleaner on a half a tank of gas and went through any connections that had to do with the ignition system,TPS or injectors and sprayed the crap out of em with electric part cleaner then drove around town for a while. Its not doing it anymore but the car still doesnt seem 100% to me . . .Im gonna change the 02 sensor once I can get ahold of the tools this afternoon just to make sure.

One other question normal Idle on a 91 240sx is what? Mines right now sits between 800 and 900

[Luke]

Engine Tune Up Data:Engine model KA24DEFiring Order 1-3-4-2Idle speed (in "N" position, No-Load) 700 +/- 50 rpmIdle speed (In "N" position, Air Conditioning ON) 1000 +/- rpmIgnition timing 20 degrees = +/- 2 degrees B.T.D.C. at idle speed

(http://www.240sx.org/faq/artic...i.htm)