Engine misfire how can I fix it?

Could a dirty throttle body course a miss at low idle

not really. i would start with basics and get the compression checked on all cylinders.

Roy

I have a 2002 ford expedition 5.4L V8. It started to run really rough. Code reader said #7 cylinder misfire. I replaced all plugs and coil pack on #7 cylinder. It runs better but It still lags. Code still pops up as #7 cylinder misfire. Also, I have white smoke(which stinks) coming out occasionally. Any help would be appreciated. Thank you.

Next step is to do a compression test and check the injector

P0307 Check the no.7 compression and injector