My 03 silvaredo Z71 5.3....just started yesterday. 128000miles. I started her up to leave the grocery store and noticed she was idling really low and a little rough as I pressed the gas pedal she did nothing. I put her in nutral and she would no rev unless I pressed the pedal very very lightly and she would rev smoothly If I pressed any furthur than about 1/2 inch she would spit sputter pop and carry on. It I pressed lightly and got her revved up and held her she was smooth but when I smashed the pedal furthur she would spit sputter pop and go back to idle.....HELP ANY IDEAS...check engine light has been on for about 3 years :frown:

1. error codes????????????????????????????????? go to autozone/kraken's/schucks/advanced/petshop boys - they'll all scan for free.
2. i do not think you have single cause, though would've been nice. sounds like you have at least bad timing/fuel problem. might be just throttle position sensor.... there's always hope, ya know.
get her scanned, please.
oh, and to have full picture of the damage, do drive cycle, please:

A complete driving cycle will perform diagnostics on all monitored systems and can usually be completed in less than fifteen minutes.
Performing a GM OBD-II Driving cycle:

Cold Start In order to be classified as a cold start the engine coolant temperature must be below 122°F (50°C) and within 11°F (6°C) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
Idle The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
Accelerate Turn off the air conditioner and all the other loads and apply half throttle until 55mph (88km/hr) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
Hold Steady Speed Hold a steady speed of 55mph (88km/hr) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
Decelerate Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 20 mph (32km/hr). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
Accelerate Accelerate at 3/4 throttle until 55-60mph (88-96 km/hr). This will perform the same diagnostics as in step 3.
Hold Steady Speed Hold a steady speed of 55mph (88km/hr) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
Decelerate This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.

My 03 silvaredo Z71 5.3....just started yesterday. 128000miles. I started her up to leave the grocery store and noticed she was idling really low and a little rough as I pressed the gas pedal she did nothing. I put her in nutral and she would no rev unless I pressed the pedal very very lightly and she would rev smoothly If I pressed any furthur than about 1/2 inch she would spit sputter pop and carry on. It I pressed lightly and got her revved up and held her she was smooth but when I smashed the pedal furthur she would spit sputter pop and go back to idle.....HELP ANY IDEAS...check engine light has been on for about 3 years :frown:

your check engine light was on 3 years and now you are asking questions as to repair problems.....by now operating this vehicle with this check engine lt on may be very expensive repair due to your negligence....DTC will be needed but by your total response posted i'd say catalytic converter failure due to the failure by you to address the check engine Lt 3 years ago....