1998 mazda b3000 4wd. 201k miles
Im getting a p0306 code. Replaced the wires first, still got a misfire. Replaced plugs and ignitiom coil and STILL getting a misfire :/ any one ?

 

Have you checked the fuel injector for cyl #6? You could try swapping it with another and see if the misfire moves with it.

 

Welcome to the forum

P0306 misfire #6 cylinder

Cold engine
Unplug the 4 wire connector on coil pack, so no spark
Crank engine over a couple of times
Pull out spark plugs 5 and 6
Compare wetness of #5 and #6 both should be wet with fuel
If #6 is dry then fuel injector is plugged or bad

If both are equally wet then #6 has compression problem, you will need to do a compression test on ALL 6 cylinders
All spark plugs need to be remove for the test
3.0l engine should test at 160+ PSI in each cylinder, but numbers vary depending on gauge used and battery condition(crank speed) which is why you test ALL 6 cylinders to get a good baseline

 

I had the same problems a few years ago. It was the plug on #6 injector. I would check this very close if I were you. the part was like $12 at the parts store. No problems since...

 

I have had the same on my 2001 V6 3.0 Ranger. I kept coming up P0306 during idle. I found an exhaust leak on my drivers side where the exhaust manifold is bolted in by two bolts connecting the rest of the exhaust. One bolt was broken off by previous owner. I clamped it down and I no longer have a leak and I don't have anymore rough idle. I was losing power at that leak and I am guessing that was causing my fault on my number 6 cylinder. So far it is holding up.

My 2 cents is to check your exhaust manifolds and the vacuum lines. It could help. I went through and replaced all wires and plugs along with a new coil. She runs real good now. I got 174k and next is to tackle the ball joints and shocks.

 

I got the 2000 engine; same issues, just swapped plugs and wires, best to change the coil too?

Could a fuel filter change affect this error?