Nissan Repair: Hesitation on hard acceleration, fuel pressure regulator, leaky injector

Question
I have a 1990 maxima that hesitates and sometimes dies on hard acceleration only. It seems to be running rich at idle. If allowed to die the car will not restart as if the ignition system timing is off. It also idle at 1300 . It only seems to idle that high only in closed loop and it also seems not to hesitate when engine is cold (open loop).

Answer
Carlos,

Sounds like the car has a bad fuel pressure regulator or a leaky injector or two.  First, replace the fuel filter and then check the fuel pressure.  Make sure the air filter is clean too.  Now, the car should start easy if you have diagnosed and corrected these.  Take the sparkplugs out and you will notice if any are really black and wet.  Others should be gray normally.  If a plug is black and wet then that cylinder probably has a leaky injector.  Also, when you check the fuel pressure just turn the key on and let the pump pressurize the system and then turn the key off.  If the pressure drops to zero quickly, less than a minute, you have leaky injectors or a defective fuel pressure regulator.