What kind of spark plugs did you install? The 5.9 engine seems to work best with copper spark plugs. Might also check the resistance with your new spark plug wires - perhaps they may be defective? Lastly, how old is your battery? I'm hoping that it reads more than just 12 volts..

 

platinum plugs from napa. And I did get new wires just haven't found the time to install them. And my battery is probably approaching 3 years old. I don't remember the exact reading I got on it and I wasn't able to load test it. Just used my dmm to test the voltage and It was at or around 12 volts with no slow cranking in the cold mornings.

 

Might want to swap those platinum spark plugs for some copper plugs, in addition to going ahead and installing those new spark plug wires. Platinum spark plugs are known to cause sporadic issues with these engines.

 

Did you address the plenum gasket issue?

 

As suggested get rid of the fancy I/r plugs. Plain copper is best for these motors. Couple of things, there is a tsb for plug leads routing follow it. Ign coil restance test is ify at best, there cheap replace it. Dizzy cap should have brass terminals not aluminum. Swap it out if it does have aluminum ones. Cheap leads, nothing under 8mm in Dia, and not cheap blue Napa wires lol.

Oh and my fav, comp test did you do one? If not do it.

 

update #4, 97 dodge ram 1500 with 5.9 magnum. miss fires mainly on cylinder 2 but I will also get the p0300 and cylinder 6 miss fire according to AutoZone and a snap on scan tool. The miss fire only happens under heavy acceleration and idles just fine. tested battery and tested good, replaced both the spark plugs and wires no change. resistance tested coil and was within specs. Had a lot of work done to the truck within the last year, new heads, new tps, new distributor cap and rotor, all new gaskets for everything, new transmission with sensors and a new timing chain. Miss fire only recently started happening. Just bought a fuel pressure test kit to test my pressure and will also be buying a compression test kit. Don't know the specs for my injector but would love to get them. Been chasing this miss fire close to a month now. Truck is also slow under heavy throttle (75-90%) really slowing down around 3,000rpm and wont shift up unless I let off the throttle. Truck accelerates better under medium to light throttle but sure does suck trying to get onto the freeway. No rich or lean codes, MAP sensor at idle running 1.2V average while upstream sensor at idle running bouncing up and down from 0 to 1 volt. Don't know if any of this information is of any help to anyone. My brain is melting trying to figure this out and buying a new truck or engine isn't a option for me.

 

The information regarding the injectors and the fuel pressure should be in the factory service manual - download the copy for your year truck here and take a look - https://dodgeforum.com/forum/2nd-gen...e-manuals.html

 

thanks

 

What plugs are in it? Still original crank sensor?

 

How old are the plugs? Have you checked the gap on them. My '96 developed a misfire and when I tore it down for a tune up (ended up removing the upper parts of the engine and it took 4 months) I found two plugs with little to no electrode left. They were burned up to the insulator.