Bad code on cyl. #4
I have been chasing a problem on my 96 4.0 Ranger. Autozone pulled a code of P0304, that's a problem with the # 4 cylinder. The engine runs rough when first started but after warming and driving it it seems to run just fine, but somewhat sluggish when trying to increase speed quickly.
I have replaced my spark plugs, fuel injectors and fuel filter. I am getting a spark when I ground out the #4 spark plug to a ground on the engine. I even tried a different plug wire with the same results. I also have tried chasing a possible vacume leak with starting fluid without any success.
-If it's a vacume leak why would it be to a specific cylinder?
-If its the injector after i replaced all six then why still #4?
-Electrical spark issue? Is the spark not strong enough? Need new coil?
Can anyone give me some directions to investigate, before I decide to take it to a shop