I have a 2007 ford f-150 4X4 1/2 ton pickup.2 months ago truck was shaking and engine light came on. Come to find out #2 cylinder had very low compression. Took heads to get done. Had 2 bad valves. Heads were re done. Ran great. Few weeks later. My truck started shaking. Only sometimes(missing) put scanner on it. Now showing error code. On #2 cyliner again "spark plug, wire, or coil". Well I have replaced these already. The coil is new and the wire new. And spark plug new. And is fine? The only thing I can think of now is a fuel injector on that cylinder.(Right after I had my heads done.I did have my fuel injectors flushed and cleaned). Im going to put on injector tmmrw. Has anyone ran into this probelm? Or is there a sensor also on the coil or something. Please help.