Ok so the problem is I have a REALY bad miss around 2000rpm it's a 95 f250 5.8 5speed with 120xxx miles on it and it has good compression it has new cap rotor plugs and wires on it also new fuel filter . Fuel pressure is good and the fuel pump volume test tested good and The cat is not blocked. The miss fire is common to all cylinders. I cleaned up the computer ground and still nothing I changed the map sensor and ignition module on the fender with known good Parts off of running truck and still nothing. What else is there to check I'm running out of ideas and it seems to run worse when it is damp out so I definitely think it's something electrical. Any ideas would be great

 

Check the routing of your wires. I had a similar issue on my truck and found some of my wires were just routed wrong and that lead to the misfire all over. Sometimes the simplest thing is what it is. Good luck.