I have a Ford Expedition 2000 with the 4.6 liter. I have been missing and shaking at stop signs and a slight lag when i accelerate. I pulled the code 307 to lean on bank 7. I had this happened about a year ago and I cleaned the IAC and it fixed it. I again cleaned the IAC, MAF and throttle body and it did no good. The plugs are pretty new so I doubt it is a plug. Do you think the IAC went bad? Should I just replace it. Also the plugs look really hard to get to because of the fuel line. Can you move the fuel line up so you can get to the plug. Any help would be appreciated-Thank you

 

P 0307 means misfire on cylinder 7. I think you confuse it with P 0171: lean condition on bank 1.
A misfire on a single cylinder is most likely a bad plug/ wire or if so equipped a bad COP. Oil outside the plug can also cause misfire.
Another possible cause could be a bad or dirty injector or circuit to that injector. Or loss of compression on that cylinder.

I don not know how to best access the plugs.