My son's gmc 4.3l hesitates upon acceleration. I have checked the coil, fuel pressure, replace the air charge sensor, new fuel filter, new air filter, new 100k spark plugs, cleaned the egr, checked the TPS, cleaned the throttle body. Can't get it to stop.

it's possible that you could have a bad fuel injector.. also you should check your fuel pressure.. maybe you should try changing your fuel filter if it hasn't been changed in a while.. but I also think you should do a compression test, you could have low compression in one of your cylinders.

you either have a plugged fuel filter, a plugged converter or a bad mass air flow sensor

try some lucas fuel injector/fuel stabiliser

COULD BE FAULTY TPS SENSOR, CLOGGED AIR FILTER OR FUEL INJECTORS NEED CLEANING.IF CLOGGED AND DIRTY THEY WILL CAUSE LEAN FUEL MIXTURE.HAVE FUEL PRESSURE CHECKED.SHOULD BE 53 - 63 PSI.RIGHT MANY NEW VECHICLE FUEL PUMPS SHUT DOWN 5 YEARS USE.FUEL FILTER IN GAS TANK CANT CHANGE IT UNTIL REPLACE FUEL PUMP.HAVE PRESSURE CHECK OUT WEAK.FUEL PRESSURE WILL CAUSE HESITATION ON ACCELERATION.

How is your charging system? Sounds to me like it's not charging your battery, so it runs until the battery cannot support the ignition load.

Hello/ Yes it can, but it is not the only possible cause. There could be an air/fuel mixture problem. This may be caused by one of the following: Oxygen Sensor, Coolant Temperature Sensor, Manifold Absolute Pressure (MAP), Mass Air Flow (MAF)Sensors, or the Fuel Pressure Regulator. I think that you need to get the codes from the ECU/PCM. These can be obtained from AutoZone, Advanced Auto, Pep Boys etc. free of charge. If there are no codes, you'll need to go to a reputable service center and ask for a diagnostic. They will generally deduct the amount for the diagnostic from any work preformed

vacuum hoses, ,connections to air intake areas

could be one of your o2 sensors ,coil pack on your spark plugs could be them,clogged catalytic convertor pretty hard to dtermine could be these.hook it up to scanner to make sure it should give you code

try a new one or try fuel filter

replace the fuel pressure regulator and the fuel filter, the pressure is low.