1996 Chevy Truck sevice engine soon light

A lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

the maf has just been changed
fuel injectors i ran fuel injector cleaner thru already 2 times by adding it to the gas tank

as far as leaky vacum i sprayed carb cleaner on all of them and the motor didnt jump up and down

egr vavle i don't know how how to cheack that and fuel pessure i was going to check today also was going to change the fuel filter due to i dont know how long it had been since its been change

so if you could explain really fast how i can check the egr vavle operation

You need a vacuum pump hook it up to the vacuum nipple on the EGR valve and pump it to 10inch-the engine will either stall or idle rough

so if it dies its no good and if it stays running it is good?

If it dies out or idle erractically it means its good-if nothing happens when you pump it up its carboned-up-not opening. get back with some results to include the other stuffs I've mentioned earlier.

i just went out and drove the truck and it ran just fine no problems i dont understand thanks for the help i was told that it could be the 0s sensor due to it has a 40 series flow master true dual exhaust?