I have a 2000 F150 with a 4.6, I have changed all plugs and boots and the truck was still missing bad. I had a code check done and it showed the EGR valve had bad flow and the #8 cyl was misfiring. Changed the coil on #8, changed EGR valve, changed EGR valve solenoid and no better. Now it won't put out any codes i drove it about 20 miles and no check engine light. Any help would be appreciated.