04 Canyon losing power

My 04 Canyon 4x4 loses power shortly after driving it for the first time each day. It’s as if fuel isn’t getting to the engine. It chugs and putts along–seems to idle relatively normal–but very little power when I hit the gas. I have discovered that some times shifting it to neutral and revving the engine a few times fixes the problem–but can always fix it by simply shutting off the truck and re-starting it. Once re-started it works normal again and I have no other problems–until the next day. The local garage had a fuel pressure gauge hooked up to it while it was acting up, and noted that the fuel pressure did not drop. Nobody seems to know what’s going on with it…any ideas?