how many inches of vaccum is a 7.3 idi supposed to make?? i have spongy brakes and a really weak cruise control, unloaded and at 65 it will not keep the truck at that speed even up the smallest grade. like a off ramp.

 

A good working pump will usually have at least 25" of vacuum and not fall off too fast when you hit the brakes. Check all the hoses, make sure they're all plugged in under the hood.