1994 BLAZER full size

I Am Having Problems With My Blazer.. It Will Turn On But The Idle Will Just Go Crazy Up And Down Then Just Die... I Will Idle It For A While Then It Will Get Stable Then I Will Try To Put Reverse Or Drive And Again It Will Die.... I Really Need Help On How To Get This Truck Running Again.....

Thanks For Helping.

Have you tried hooking the scanner and check that all your sensors such as, throttle position sensor, idle air control and oxygen sensor are all working correctly? Seeing as this is all controlled by the computer one of the sensors is likely to be your culprit. If you have an Auto Zone or Advanced Auto they will check this for free. Maybe NAPA too but not sure.