Loss of power when accelerating?

Vehicle will drive fine and start up fine, especially the first time of the day. I can drive it for an hour or so in town and then all of a sudden it will start losing power. I usually notice it when I'm coming to a complete stop and then I go to accelerate, I have no power the van does not stall out, but when I hit the gas pedal the engine does not rev up or anything. If I just barely touch the gas pedal it will very slowly start to accelerate if I'm on an incline it doesn't try to go at all it will sit there and jerk as I'm tapping on the gas. It has stalled out a couple times but only after trying to get it home so had to drive it a little distance while I was acting up like that if I could stay on a flat surface and keep the gas pedal barely pressed it will eventually start to accelerate slowly but can never get it passed like 20 miles an hour. If I let it sit for a couple hours and then try to drive it again it's fine until this issue starts all over again. Only after I've been driving it for a little period of time before this issue starts up again. I've heard it could be the vacuum lines the fuel pump and filter the throttle body I just need to know where to start checking and I'm not a mechanic so meaning a little more explaining on an issue but I understand basic mechanics so in the past I've been able to figure out most issues on my own or YouTube is great. So just let me know what your thoughts are on where I should start.