I have a obd2 P0303 cyl #3 misfire code ,changed plugs,changed wires ,swapped coil temporarily for one i know is good , this is on V-6 auto continuous check engine flashing- car runs fine drives good then irradic idle and will stall in gear. At other times it runs and idles smooth? changed IAC , still the same ,checked for vaccuum leaks can't find any?

 

Flashing MIL means just one thing, - she's missing. Fuel first, then ignition. Change the Fuel filter lately ? What's the pump pressure reading?

 

Mine did this too except im a 5.4L. When she is missing on one cyl the truck idles a little rough but will not stall. Once I changed the coil and plug she runs smooth but when i pull up to a stop light the idle will jump and fall and eventually the engine would die. This went on for a month or two until the coil fouled out again so i havent done anything to fix it yet. There is a grounding wire that screws into the fire wallthat let the water drain in and drip down on top of the COP that i have fixed with a lil silicone. I would rather it always run a lil run rough than cut off on me every time i stop so i havent replaced the COP.

 

it has about 30psi on the fuel rail , could a single bad/clogged injector be causing the problems? is 30 psi enough or is there a fuel pump problem ? thank you in advance for any help