Misfire on cylinder 3

I think you have an ignition module which may be bad.

DOES THIS VEHICLE USE COIL PACKS? MOST LIKELY (3.)....1 THAT FEEDS CYLINDERS 1&5 ....1 FOR 2&3 AND 1 FOR 4 AND 6......OR SOMETHING SIMILAR TO THAT. CHECK FOR A BAD COIL THAT FEEDS 4 & 6 TRACE PLUG WIRES TO INSURE THAT SAID COIL FEEDS #'S 4 & 6

If you pull the plug wire from the spark plug on cylinder 3, is there any oil, water, or antifreeze in there? Have you removed the plug to see what condition it is in? If it is black or oil-fouled, you should replace it, or better yet, the entire set of spark plugs. When the coil pack was replaced, was the plug wire replaced as well? I have seen a stuck fuel injector cause your problem before, because the cylinder does not get the right amount of fuel, running either too lean, or too rich.

There are a few things that can cause an engine misfire and hesitation. Does your van have a CoP ignition system? (Separate ignition coils for each spark plug) Or coil pack? You may have bad ignition coil(s); that would cause a misfire. If you have a dirty/clogged/leaky fuel injector for cylinder 3, that could also cause a misfire condition. When you replaced all the spark plugs, did you look at the plug from cylinder 3? Did they all look the same? Sometimes you can get clues to what is going on in your cylinder by how the spark plug looks: if it's white or glazed you are running too lean and could indicate fuel injection problem, if it's got burnt oil on it and it's sludgy you may have a leaky gasket or worn piston ring that is letting oil up into the combustion chamber and fouling the plug, causing a misfire. If your check engine light comes back on and it's the same misfire code, have the coil for cylinder 3 checked to see if it's weak or bad. Or you can do a home remedy check and swap a known good ignition coil from another cylinder to 3, reset the code, and see if the misfire moves to another cylinder. If it does, you know the coil is bad. You can pick up an ignition coil for pretty cheap on the internet ($30-$70) if that's the problem and they're simple to install (a pain if they're on a cylinder that's under the intake manifold, but just because you have to unbolt a bunch of stuff to get to it...time consuming but not too difficult). I have a 2001 Mazda Tribute and had a couple of ignition coils go bad, causing misfires. This seems to be a semi-common problem for early 2000's Mazdas.

was the any oil on the coil boot? you can have a weak injector or a stuck vavle

did you replace only one spark plug? that can cause issues because of differences in resistances between cylinders. also, did the map code stay off after replacing
?

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The Code(s) should be telling the specific cylinder(s) that are misfiring. Do you know waht the code is?
Target those cylinders 1st before testing the unaffected cylinders.
The following should isolate the problem(s).
1. Spark plugs - take out-reconnect back to wires and test spark plugs for getting sparks. If none: Don't replace them yet. GO TO 2. If the spark plugs are worn, dirty them replace them.
2. Remove spark plugs form end of ignition wires and test for spark from the wire. If none: Don't replace them yet. GO TO 3.
3. Remove the wires from the coil connection and test the coil for spark for each cylinder. If none: Don't replace it yet.
4. Test each spark plug and wires this way.
5. Coil Packs normally provide fire for 2-cylinders at the same time. The two are paired across from one another.
6. Test the coil for fire, amount of fire and if there is both cyclinders firing.
Misfire and the O2 Sensor got replaced??
Good Luck and get back with me if you need additional help or if this solved the problem.

Code P0301
Ignition Coil Pack
Ignition Cable
Spark plug
Clog or dirty fuel injector
Evap canister purge valve
Engine Compression
fuel pressure

you have 3 type of engine for your truck
2.3L 4 cylinder
3.0L 6 Cylinder
4.0L 6 Cylinder

need to know that type Engine

The reason why the service light come on because it is a hard code
not a soft code.

Let me know

A multi misfire may mean that one or more of the following has happened:
Faulty spark plug or wires, Faulty coil (pack), Faulty oxygen sensor(s), Faulty fuel injector(s), Stuck/blocked EGR valve / passages, Faulty camshaft position sensor, Defective computer.

The engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wire, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the the problems were faulty fuel injectors. 

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

Good luck and hope this information helps, keep me posted, be glad to help you get the truck running 100% again. Not sure if your running a K&N air filter, and if you are there may be a flim of oil on the MAF sensor that is making you run lean. You may want to spray down the MAF sensor with a can of MAF cleaner.