Welcome to forum!
Congratulations in advance for purchasing the best D@mn truck ever!
The 7.3's are a hell of a motor, but they need to be taken care of.
I would keep an eye out for the stock airbox, sometimes the clips break and the boxy wont seal (excuse to buy an intake). I would take the intake tube off and make sure the turbine wheel is still sharp. If it looks worn then this means that the engine has morethan likely ingested dust.
Look at the oil. Fresh oil is the life of these engines! The injectors fire off of oil presure. look for genaral leaks. My 2001 has 209,300 miles and doesnt use any oil between changes.
Check tthe fuel filter s just unscrews. If it or the air filter is really dirty, or the oil is really wore out, the truck was probly not taken care of.
Is the tires on the front are unuaully new or eat up it may have a front end issue. these heavy engines are hell on front end.
For the most part these trucks are pretty solid. but that is what i have learned about thee general problems that may occur