I have 2001 chevy s-10 exteneded cab and I have a secondary ignition problem with the third cylinder it is misfiring. I replaced the air intake, dis coil, plugs, plug wires, and even the ignition module, and the muffler, all uprgraded with high performance parts. It ran great for about three months and then I started getting the misfire on the third cylinder. I took it to the shop and the put it on the obd reader and it came up as a secondary ignition problem. since then I’ve removed the muffler so I’m running with an open pipe but I do still have the catalytic converter on. It does not always misfire, if i play with the throttle I can keep it from misfiring. It only happens when the vehicle is under load, like going up a hill, when I first take off, or if I give it to much gas. Before I start replacing everything on my truck is there someone who can tell me what to try and do next. Could I have a bad injector, fuel pump, or fuel regulator, wouldn’t that have come up on the obd scanner? Can I fix the problem with a chip? Someone please help because this is my primary source of transportation.