Re: 95 f250 not running well
i have no clue about your problem mtx1 but if you are just looking for ideas, here are a couple things that will affect engines when the warm up.
1. ignition coils (most generally loss of spark when going bad)
2. module and or stator in the distributor ( again loss of spark, replace as pair)
3. heads or intake manifold (will allow coolant into cylinders after warmup, rare conditions)
4. there are numerous valves and that will open after warmup and could be the cause of a vacuum leak or similar.
i would start with #4 see if you can plug a line and make a difference but do it one at a time.
maybe while you are looking around you will come up with something.
let us know any more details about your problem that you can give !
i would rather push my Ford than drive your Chevy !