1995 f250 7.3 powerStroke Truck has been sitting for 3 months now it has great power unless I get on it hard then the check engine light comes on and it falls on its face

 

Check you oil level, make sure your oil is clean, does the cel stay on long enough to pull codes? any mods done to the truck; chip, programmer, sticks, etc, do you have any gauges so you can see what the engine is doing? more info please...

 

Get the codes. The light does not have to be on to get the codes.
Auto part stores scanners do not work on these truck you will have to go to a reputable shop

 

I don't have the needed gauges oil is clean have been running injector cleaner in it strong and it seems to be getting better not doing it hardly at all anymore no mods