Engine Performance problem
2001 Ford F150 V8 Two Wheel Drive Automatic 133000 miles

i have a 2001 ford 150 every once in a while when i start my truck, i turn it on it revs really high then drops below 500rmps and dies. when i try and start it a few more more times same thing. when i let it sit a few minutes and feather the gas i can get it to run and then it is fine. I ran a obdII scaner on my truck and said my IAC was at 42.2% was wondering if that is where my problem is?

thanks