I have a 2010 4.6 with 8000 miles on it. I purchased a 400+HP "top end kit", cams, heads, throttle body and intake from Ford Racing, and had a local Ford dealer install it. The car has a low rpm miss, that dyno tuning, and new spark plugs have not been able to fix. Does anyone have any ideas what is causing this headache for me? Vacuum line, injector, cams? Please help.