acceleration lag

I have an 89 240sx, auto, hb. Everything was fine up until today when i was driving i was having problems. when i accelerate from stop (~700 rpm idle) the tac will go up and the engine will rev but the car will not actually move until about half a second later; somewhat of a time lag. I also noticed that my car almost stalled at one of these starts and that it would shift in and out of one gear (i think 3rd/4th) when its close between them. All this began as of today and I checked the tranny fluid/oil which are both fine.

PS: yesterday i changed my oil, air filter, and tightened one of my fan belts (cam/alternator)

transmission issue. you may need a rebuild.

update...

Sorry for giving the wrong info but its actually a lag between when i hit the gas and when the engine actually revs up (ie: throttle possibly?). Also, i had a hard time starting my car today; the engine would turn over but it would not start up until i gave it some gas (and its fuel injected). please can someone help im worried about my poor 240 :(

Could be a lot of things, if the engine isn't revving up right away could be the throttle positioning sensor. Could be your MAF, get some maf cleaner and spray that up a bit and clean it off.

Do lower RPMs seem sluggish? make the car chug a little? I doubt this is it, but if your spark plugs are old, maybe they need replacement. Check for vacuum leaks too.

yeah im thinkin bout just takin it into a mechanic. it seems like a fuel injector problem, possible engine flooding. idle is usually fine (~700 rpm) but when i give it gas it drops down to about 500 rpm and basically stalls. high rpm's are essentially fine

another update.. i checked the ECU and got the ol' 55 (no malfunction). If the ECU says my car is fine, but its not, then I dont know what the problem is! probly a job for the mechanics... if anybody's got any info i would be glad to hear it!

just thot i would post a reply because i fixed the problem. relaced the coolant temperature sensor (to ECU, not gauge). ran me about $50, very easy fix.

i have a 1990 nissan 240sx and i dont have a ecu to fined the problem but i have an idle issue and when i give it gas it boggs down before it picks up. it also has trubble stayin runnin when not in gear. the idle fluxuates as well. plz email me at nathaniel.woodhall@dover.af.mil if u have any ideas what could be the problem..

ps. i changed the plugs wires and oil nothing helped.

sounds like the same problem I had. replace the coolant temperature sensor (make sure its the right one) its a very easy fix. only cost me about 30$.