Engine misses and very hard start

My truck has a very hard time starting. It will crank but not start. The engine misses and it is hard to accelerate especially uphill. Almost like a timing or air/fuel problem. I have replaced the plugs and plug wires. I took it to mechanic shop for diagnosis and they said it had jumped time. But I changed the timing chain and it hasn't jumped, it was a little stretched so I replaced it anyways. I don't know what to do next.