ya my truck misfires on start up!!!

the truck on the startup it has that non mistakable misfire shacking not that sevire. it revs out to too about 1300 rpms then the misfire stops it takes a few seconds for it to do this. i have replaced the spark plugs and wires a few times and nothing has change. i have taken it to the shop and they can't find the problem. i am really tired of this so has this happen to anyone or advise is really helpful.

thanks swick

 

My guess would be the coil pack.