my truck idles nice but when i go to accelerate it breaks up .i plugged in a code reader and it tells me cylinder 3 and 5 are misfiring .it will clear after about a couple of hours of highway driving.could it be i have a bad coil?

 

Sounds about right, coils tend to fail on those older trucks, Remove the suspected coils and just take a look at em. If the rubber boot is all brittle and when you squeeze the end it starts to crack and break it may be time to replace them on top of the coils internally failing. If you can get away with just 2 Ignition coil installations your a lucky guy.