Loss of power?

'01 Silverado with the 4.8, sitting at 160k right now. I'm starting to notice a loss of power in the truck, when pulling out and accelerating it doesn't put you back in the seat like it used to and when going up a hill you have to force a downshift to not lose 15-20mph... it just seems like I'm pulling an invisible trailer back there. The fuel pump is about 1 year old, fuel filter less than 3 months, plugs and wires are about a year and a half old, PCV valve about 6 months old, fuel pressure regulator about a year old... Any ideas?

No check engine lights or codes or anything like that either - also cleaned the MAF recently and the K&N air filter is clean.

The fuel pump is about 1 year old, fuel filter less than 3 months,

Not sure if it would cause a loss of power but.... Aftermarket fuel pumps seem to only last 6 mo - 1 yr unless you get a delphi or other high end pump. The fuel filter should ideally be replaced at time of fuel pump replacement. Something to do with new pump pushing sediment into filter....
It may be worth while to check your fuel pressure, just to make sure everything is up to par.

Also, Do a quick search on fuel pumps in this forum..... Many people have confirmed the crappy aftermarket pumps....

with no codes you must check fuel pressure. lots of issues with pump replacement screw ups along with defective pumps/wiring/relays/grounds/connectors etc...