I haven't had the truck long so I don't know if it's normal. It is a '97 4.6.

If I start the truck on a cold day and don't allow it to warm up, it seems to lack power and the engine "roars" until it gets warmed up. Is this normal?

 

Sounds like a bad thermal clutch on the fan. It's staying fully locked which makes it real loud and robs tons of power. When it releases the truck will immediately quiet down and the truck will be much quicker. Try a new thermal clutch but not an aftermarket one. Many people including me have had trouble with new ones doing exactly what yours is doing. Get a used one from the junk yard like I had to for about $15.00 or from the dealer for $120.00.