alrighty so here's what i have going on. I have a 97 B4000 (basically a 97 Ranger) 4x4 4.0 OHV with about 150K miles on it. I had the ever present header crack and losing a little bit of coolant over time and so i decided to replace it on my own. I am not a certified mechanic, and so youtube, books and online forums worked to get the heads replaced and all the parts put back together (probably correctly) I did not replace the lifters when i did the upper rebuild, though I checked all of them for wear and damage. soon after i put the truck together, the truck began to burn oil. I didn't know the truck was burning oil until it developed a knock. took it into a mechanic shop and they said i had hardly any oil in. they filled the oil, the knock went away. now its been 7000+ miles later and the engine is knocking, and still burning oil. it seems like its getting into one of the compression chambers because i can see some carbon build up and light oil on the spark plug. so here's where i get confused. The engine only knocks when its under strain. i can rev the engine in neutral, and it doesn't knock, it doesn't knock when just idling, it only knocks while driving. I am hoping someone on here can tell me its not a worn piston ring because then i'm just F***ED. I really cant take the engine apart again in part to the cost of replacing all the gaskets and the time without being more certain on what is happening. this truck is my main driver, so i cannot be without it for too long. if i can narrow down what is likely the issue i can plan ahead on how long i need and try to find a long weekend when i can get off work. I am wondering if a broken rocker arm can cause oil to get into where the spark plug is and burn up? (though there is no sign of blue smoke at all, i had a friend follow me onto the highway to watch if it looked like i was burning oil). So far i just put in about a quart every two weeks but that's only cause i live close to my work and the truck doesn't run for very long. any advice would be helpful, but no i cannot afford to take it into a real mechanic and have them redo my upper engine rebuild (though im like 99% sure it got put back together fine)