i have a 2003 ford f150 4.2L. i changed to bosh plugs wires also changed coil pack fuel sensor bank 1 upsream and fuel filter. but get the pocodes po135-316and 300. its got me stumped as this is my only ride. it has around 280,000 miles. it runs smooth with just a little rough idle.
random misfires are the hardest to decipher. But on that, I'd smoke test the intake to check for vacuum leaks, and also do wet and dry compression tests on all cylinders to see if engine is just flat wearing out