Q: Engine knock and low engine power

Good day, I purchased a 2009 Dodge Ram 1500 approximately 6 months ago, knowing with a minor tick in the engine, I thought it was still worth the price. Over the months, I noticed the tick got louder, louder and louder now becoming a knock. I have had it inspected multiple times, had the Valve Lifters replaced, was informed that the rods and lifters were sturdy and tight that there was no visible sign where it could be causing the knock. So I have new lifters, the Engine Light is not on, but every now and again the Engine Light will go on. Usually for a day and a half then disappear. This happened twice. It has trouble climbing fairly small hills(roads) and will not pick up speed while climbing unless I completely press the accelerator pedal down then it picks up speed easily. As of right now though, climbing up a road, it usually sticks at 30km/hr at 2000RPMS until I get near the top. If you could please help me diagnose this, it would be greatly appreciated! Thank you. -Carter

My car has 86150 miles.
My car has an automatic transmission.