Nissan Repair: maxima stalling, fuel pressure gauge, leaky injector

Question
QUESTION: I recently bought a 95 maxima from a friend. The problem is  it stalls on me when im stopped by a light or in traffic. So far it seems to stall only when the car is in gear and there is also a slight lurch when the car has been stopped and i accelerate somewhere between 15 and 20 mph sort of feels like its stuck for a second and then it lurches a bit and continues along just fine. Usually when it stalls i have no problem starting it up again although i must give it a little gas. After the car has been driven around for a little while and has seemed to have warmed up i dont seem to feel that lurch and it doesnt stall out on me either. The other night i drove it on the highway for the first time and i think felt the transmission shifting as i slowed down. I brought it to my mechanic and he found a ripped wire that he said was causing some type of problem in reverse he said that i should get better gas mileage now that he replaced but he couldnt promise that the stalling would stop. I know that maximas are known to have bad MAF sensors but i think he told me mine checked out fine.

ANSWER: Eli,

Check for leaky injectors.  From what you describe it sounds like the injectors are leaky when cold and after warm up the car compensates for the excess fuel.  Get a fuel pressure gauge and connect it to the fuel rail.  Like the valve on a tire.  Then start the car and look at the fuel pressure, on the gauge.  Now, turn off the engine and if the fuel pressure drops rapidly you have a leaky injector or two.  If this is the case replace the injectors.

---------- FOLLOW-UP ----------

QUESTION: i sent you a question last week and  have realized a little more since i sent it so if you dont mind id like to present it to you again with more info. the 95 maxima has only 103,000 miles on it. as i told you it seems to only stall in idle and when in gear. but after driving around a little more i have realized that in the hot humid and sticky weather it doesnt stick to these rules. it gets frigged up constantly and even in park it idles very rough and the rpm's shift up and down. i find  it increasingly hard to accelerate in the humid weather, even when i floor the gas and the rpm's go to 3 it doesnt pick up and seems to be stuck and like its about to stall when it does finally move forward it does so with a slight lurch this will happen even after the car has warmed up and has been driven around for a while but in the cooler less sticky and humid weather it seems to pretty much be fine except an occasional stall here or there when idling. after it stalls it usually start without incidence except sometimes i must give gas very my brother thinks its an air issue and told me to clean out the IAC can you please share your professional advice i did read what you sent me and i will have my brother check it (he's the car savvy one) but now that this is happening even when the car has warmed up can you tell me if there is something else causing all this   thank you

ANSWER: Eli,

Something I did not ask is if the plugs have been changed recently.  Old sparkplugs will do what you say.  If they have been replaced and this is what it is doing I would be checking the idle air control valve since that is what controls the idle of the engine.  Hunting for an idle speed is usually associated with this or the manifold absolute pressure sensor.  That is what tells the idle air control valve to maintain a certain idle.

---------- FOLLOW-UP ----------

QUESTION: My mechanic said the spark plugs were fine so i had him clean the idle air control valve and it didnt change anything. I installed an aftermarket MAF sensor and the cars problems changed - that lurch and slow stalling out where the rpms dip very low pretty much stopped happening but when i start the car it either stalls completely or the rpms jump between right above zero to 1200 then it evens out or if i give gas (i think when the ac is on it will stall completely but then it almost always start on the second try). There is also a new problem that the car  starts to jump and lurch right when i begin driving after i am completely stopped but its a different feel than previously cause before it felt like the car was stalling, but now it seems to just buck and jump one time and then it smoothes out. Also when im idiling in gear with my foot on the brake and i jerk the wheel around back and forth the rpms dip and it stalls if do it a few times. I think this may happen when i slow down and make a sharp hard turn thats the only time i really stalled while driving since i changed the sensor. I am trying to return the sensor for a used nissan one but before i do I'd like your expert opinion on the matter.

Answer
Eli,

I would check the idle air control valve for proper operation.  Also, the throttle position switch could be defective and there is the manifold absolute pressure sensor.  But, from what it sounds like I would look at the idle air control valve first and be sure to check to make sure the throttle body is clean.  I think the mass airflow sensor was part of the problem but not the whole problem.