I have tried to solve this problem for awhile, and am at my wits end..... truck is 2005 5.4 with 123000 km, problem happens wot on the highway (only) when the truck has "downshifted" and the rpm's are increasing, I get to just a little over 4000 rpm then get the dreaded blinking cel and eventually a steady cel, always for cylinder #3 misfire. It does not do this when you say leave from a stop light and floor it, the truck revs to near 5000 then shifts gears and no problem, always at highway speed when I "kick it down". I have switched coil packs, then decided to put all new ones on anyway, changed fuel filter, new airfilter, cleaned tb, just put a new injector in #3, had the plugs done at the dealer last year, but switched out #3 for #1 and still have had no luck. I need help bad...... thanks

 

Any Ideas on this one ? Maybe I should have this question in the engine forum ??

 

I will post this for anybody who searches and comes upon this thread........ I feel the cylinder #3 misfire code had me focused soley on cylinder #3. The problem turned out to be a plugged cat on the passenger side (causing the misfire and power loss) A friend who owns a shop helped me figure this out, who then informed me it may still be under warrenty. Turns out it was and ford covered this under emissions warrenty free of charge. I have owned the truck for 4 years and it is now truely like a different vehicle. Must have been partially clogged ever since I bought it.