Engine idles and starts ok but stalls out whenn u give it throttle

the iac sensor is along the side of throttle body , did you give the throttle plate area a good cleaning out this is where the air path is for the IAC sensor , a lot of idle problems have been fixed with a can of throttle body cleaner and few good squirts of the stuff down the hole

Without checking your car physically, its not possible to give you any idea what it could be or not

Sounds like your throttle position sensor is gone. The throttle position sensor is a sensor that tell the computer how much gas to give the engine. I had a very similar issue with a car i had where it would be ok when it was cold or idling but when i took off from a red light after it warmed up it would just stall.

Read the following and follow the instructions for this problem.

Here are the most common causes of idle surge, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake

Try cleaning the throttle valve and the idle speed control valve. Use CRC brand spray throttle valve cleaner, about half the car will do it. Spray it into the engine intake while it running hold the idle up or it will stall out. After you have done this the idle problems should improve.

Clean your Throttle body and pay attention to the Idle Air Control (IAC) valve passageway to try to clean the IAC. A dirty or faulty IAC will cause your engine to stall at idle, the job of the IAC is to open the passage way through the throttle body to regulate the amount of air to enter the engine to keep it from stalling when the Envoy is at idle.

Start with the simple and clean the throttle body and inspect any loose or damaged wire leads to the throttle body. Replace or repair any signs of damage.

Thank you for using Fixya and good luck.

check the TPS on the throttle body It may have a too low of a voltage causing this engine to die out which is very common

Clean the Idle air control valve (IAC), it's located by the throttle body so the best thing to do is give the throttle body a good cleaning with throttle body cleaner. Do not use carb cleaner, it's to corrosive for the gaskets used on the throttle body's. Just follow the instruction on the spray can and after your done putting everything back together. Turn the ignition key's to the run position for 10 seconds and then off for 10 seconds to reset the IAC. Start the engine and let idle for 1 min and go for a test drive. If that does not work, turn the ignition to the run position and pull the ecm(BATT) fuse out for 30 seconds and then place it back in start te engine. The engine may stall but let it, don't touch anything. Just start it again and let idle for 1 min then go for a test drive. The ECM is just relearning the sensors like the first time the jimmy was driven off the assembly line. Good luck and hope this helps. Keep me posted be glad to get your jimmy running 100%. 

Start by cleaning your throttle body.  May need an Idle Air Control valve.

Question, did you replace the throttle body, or clean the throttle plate, it will carbon up and block air needed for the idling speed to be correct. Also check for vacuum leaks, as the older vehicles didn't have good vacuum hoses. Good luck