I have a 2004 dodge Dakota 3.7 six cylinder. Truck running real rough with a P0306 Code. Replaced the spark plugs and ignition coils. At idle no check engine light.

Part 3 -How to Test the Ignition Module and Crank Sensor ...

easyautodiagnostics.com > Ford > 2.3L

Mar 1, 2012 - Spark plugs for cylinders #2 and #3 get spark at the exact same time. ...voltage -12 Volts) to both individual ignition coils within the coil pack. ... Ford Mustang or Ranger (or 2.3L Mazda B2300), this is what you'll need ... for this 'Switching Signal' at the coil pack... but you can also test this ... 1991, 1992, 1993.

How to Diagnose a Misfiring Cylinder (2.3L Ford Ranger ...

troubleshootmyvehicle.com > Ford > 2.3L

Apr 3, 2012 - Bad Fuel Injectors can cause a Misfire Condition. ... the ignition system on the 2.3L Ford Mustang or Ranger consists of 2 ignition coil packs, ...

2002 ranger misfire rough idle - Discussion on Topix

www.topix.com > Ford Ranger

Jul 27, 2007 - My truck is giving the code misfire in number 4 cyl. I replaced my spark plugs, Wires, Coil packs (both of them) and all my fuil ... three (3.0L v6) go bad, the fuel/air mixture gets messed up. Judged: 2. 2 ... My truck runs rough only at idle. ...code for ford ranger 2002, 2.3 5speed. truck runs like a champ but that ...

Extremely stumped! I need the best and brightest 1994 Ford ...

answers.edmunds.com > Edmunds Answers

Check for spark at the plug ( may have coil problem).
If spark is good then do a compression check. Pressure shouldn't be less than 75% of known good cylinders.

That's Random or multiple missfire code. Have you checked for proper fuel pressure? Improper fuel pressure will trigger this code if it's too low, thus causing a lean mixture in multiple cylinders.

either on removing the spark plugs and the HT Leads might you mixed them up somewhere bet six,seven and eight.

Code p0306 means that cylinder six is misfiring. Take it to a mechanic or try to fix it yourself. Change spark plug, plug wires, solenoid.

The DTC P0306 - Cylinder #6 Misfire Detected means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #6.

Symptoms may include the engine may be harder to start, the engine may stumble / stumble, and/or hesitate or other symptoms may also be present

A code P0306 may mean that one or more of the following has happened:
Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer

Some possible solutions, if there are no symptoms, the simplest thing to do is to reset the code and see if it comes back. If there are symptoms such as 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 wires, distributor cap, and rotor (if applicable).

Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Hope this helps (remember to rating this answer and leave us some testimonial comment)

i would think a plugged fuel injector on # 6 cylinder could be the problem,or a big vacuum leak at that cylinder
a valve burnt/stuck could be but you dont see much of that anymore
could be coolant leaking into cylinder from leaky haed gasket but you would have to add coolant every so often
i would check #6 cyl. spark plug after driveing around a while if it looks new, ie no deposits on it then an injector would be what i would change next

A P0306 code means that the car's computer
has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #6.

Symptoms may include:
the engine may be harder to start
the engine may stumble / stumble, and/or hesitate
other symptoms may also be present

Causes

A code P0306 may mean that one or more of the following has happened:
Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer

If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as 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 wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

A P0306 code means that the the ECM has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #6.

A code P0306 may mean that one or more of the following has happened:
Faulty spark plug or wire, Faulty coil (pack), Faulty fuel injector, Burned exhaust Valve, Poor compression, and Defective computer. 

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 Caravan, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). The number six cylinder is the one towards the radiator and drivers side. If you are going to change all the plugs and wire keep me posted, be glad to help. Good luck and hope this helps, P0300 just means multi miss fire.