1995 powerstroke idle
 

i have 2 1995's, 2 1996's, and 1 1997 and on the 2 1995's when i start them they romp real bad for about 2 or 3 seconds then idle normally. the 1996's and 1997 doesn't. every 1995 i have ever seen romps when you start them. why is that?

They are a little different in the front cover and hpop, not sure if what would cause it or not