Nissan Repair: 93 Altima Stalls, fuel pressure gage, fuel pressure regulator

Question
I have a 93 Altima that all of a sudden started stalling when you come to a stop.  The problem starts after the car has been running for about 15 minuts.  This seems to be a problem when the engine gets warmed up. I took it to the repair shop and they have replaced the spark plugs, spark plug wires, distributor cap & rotor, fuel pressure regulator, and fuel filter.  They fuel pressure was checked and was slightly high (41PSI) so that is why they replaced the fuel pressure regulator.  The fuel pressure is now at 36 PSI in the normal range.  After the engine warms up and it begines to stall at stops, we put the fuel pressure gage back on and the pressure fluxuates irraticly with-in the normal fuel pressures.  When you kick the RPM up over 2K the pressure is rock steady at 34 PSI.  The car seems to have no problem when you are driving it until you come to a stop.  The RPM drops below 1K and gets real ratical, then stalls.  Starting is no0t a problem it starts normal every time.  They shop was suppose to do a complete tune-up on the car.  They fuel injectors have been cleaned.  The car seems to stall even worst now that all this has been done.  There was no work done on this before this started and the car is kept in the garage.  The shop thinks there is a fuel problem that is why they have checked all the fuel system componets stated.  They check the computer and have found no codes in it that indicates a problem of anything.

Answer
I would be looking at the condition when the car goes into normal mode.  After the car gets warm and the car starts reading sensors is when the problem occurs.  A sensor can be bad and not throw a code.  So, we are looking at the cheapest sensor first and that would be the temperature sensor that tells the computer that the car is out of choke mode.  Next would be the throttle position sensor, mass airflow sensor and lastly we are looking at a MAP sensor.  No way to tell with me being on the computer but that is where I would start.  You can get a Haynes manual and a volt ohm meter and start checking the sensors to those values given in the book to determine which one is bad.  Do not be mad at the shop as most are not really keen to checking all the sensors.  And, since most electronics never fail it is a turkey shoot to determine which one is bad.  And, lastly I have seen where all the sensors check good and then you find a bad wire where the insulation has worn off.  So, check the sensors and get back to me.