I have a 82 pickup 4x4 and when I start it idles at like 2500 but if I pump the gas it idles back down and stays like that, what could this be and the carb is fairly new, also when I'm driving and come to I quick stop my truck dies on me. But the truck runs good just this is bothering me help out please thanks

 

This all sounds normal. When it start you start you should hit the high idle around 2400 rpm and to disenage the high idle you pump the gas once and it should drop idle to around 900 rpm.