i have a 99 f150 with the 4.6l auto. it has a bad miss it started just on the #8 i changed the coil packs plugs and wires and the fuel injector on the #8 and now it has got worse and has moved to the #3 and 4 and now it does not that the power to even move its self.
i have heard it could be a cracked valve, a bad computer, low compression
does anyone know what it could be and where i could start

 

Could you be more descripitive on what's going on while you're trying to drive it? I'm still in high school but we have a scan tool in the shop and if a local has a problem and they come in we usually hook it up and diagnose the problem, fix it too if we can. Take a swing by your local high school and see if the automotive teacher can get a few boys to see what's going on. They won't need to drive it or anything, just plug er into the computer and scan it.

 

Are the misfire coeds the only codes or are there more....? What packs, plugs and wires were used? Some dirty gas may have washed through the injectors, I would run a bottle of techron through the fuel tank and clean those out for good measures anyway.

 

Check your fuel pressure/ regulator.

 

yes the miss fire codes are the only thing popping up. its got motorcraft plugs wires and coils and i really don't remember the brand of fuel injector. could a bad wire coming off the computer to the coil pack case this