[Lexy]

Your skimmer's pump have a build in monitoring safety switch. If there is any slight internal pressure changes inside the impeller casing or air intake restriction or motor faulty it will show down the rotation and eventually stop. Your water level must have a constant level. Since you replaced the impeller, did u check if the impeller magnet, if there is any hair line crack? From your picture, air intake line look good and not pinch. Try to unplug the power and let it sit for 5 - 10 mins, then power it back. It should run in full capacity or sometime it lagging. If it doing it again, I think it skimmer pump is the problem.