Well its getting hot here so i kicked on the old A/C, and i noticed when i am stopped at a light my blazer will miss periodically and then surge when i try to take off. This ONLY happens w/ the A/C on though, otherwise its ok. Anyone know what could be causing this? Thanks

 

How does your belt tensioner look? Is it keeping pressure on the serpentine belt through the range of your pulleys?

 

I would recommend that your remove and clean the throttle body. Sounds like you may have a problem with the IAC (idle air control) valve on the throttle body that controls the idle speed. When the A/C kicks on, the IAC will open up more to account for the additional draw on the engine. If this does not happen or does not happen quick enough, you could experience a low idle speed which is what this sounds like.