i have same problem and with same mileage, car misfires.
Did you solve what was wrong in your car?

 

I changed the plugs and wires. I used the NGK Iridium plugs and the Bosch wires, the wires are about 2 - 3 inches longer than the OEM and they aren't stretched from the coil to the plug. The plugs are difficult to get to, however,,,, remove the three T15 torx screws and about 10 of the removeable plastice body rivets and the inner fender well comes right out and the plugs are right in front of you, made it a lot easier.

 

@Transit
What was problem in your case? maybe O2 sensors?

@fireman2020
Was your car also misfiring with 1, 5, 6, 8 cylinders?

 

I had no codes generated or engine light,, it was just an obvious misfire due to the plug wires being to short.

 

My 03 H2 developed a strange miss fire pattern and lost all power and would over heat quickly. After a few hours of simple trouble ie. checking spark wire changing plugs inspecting coil packs, hooking the truck up to a scan tool, and quite a few beers. my brother (professional diesel mechanic) and I came to the conclusion that the cats must be stopped up. Because stopped up cats would create excess back pressure and heat on the engine and at a certain point would likely cause the emc to start miss firing the engine at random to keep it from getting to hot and harming the engine.
The error codes did not directly tell us that this is the problem. I gutted the cats and the problem immediately when away. This happened on my truck @ 65,000 miles.
What to look for:
engine over heating (if your tstat is good)
slugish throttle response

random miss fire codes
check engine light flashing (indicating a miss fire condition is occurring)
complete loss of power
loss of throttle response
high water temps (even after engine running only a short time)

Don't know if this is your problem but I know it was mine
hope it helps

 

had same issue around @ 90,000miles. changed plug and wires with o.e. parts and problem solved. It really only misfired when the supercharger engaged. was weird.

 

I don't mean to bring this post back from the dead but I used the infamous search button and the OP in this thread experienced the EXACT same problem as I'm going through right now. I need to know if the OP fixed his problem and if so how did he do it?

Mine is the EXACT same problem miss fires on cyl 1/5/6/8 only around 2500 rpm.

Parts replaced already with new:
Injectors
coil packs
plug wires
spark plugs
knock sensors
knock sensor harness
intake manifold gaskets
all 4 O2 sensors
new AFE dry air filter
Cleaned the MAF using maf cleaner

The only things I haven't changed out so far are the exhaust manifolds and gaskets, and the cats. I do have receipts from the previous owner I found in the glove box where the exhaust gaskets were changed and new manifolds were installed with new bolts because a few broke (all dealer repaired).

I do have an Altel scan tool and the code is P0300 multiple miss fires, every damn time!

Please help.

 

ERICHERM1, did you ever resolve this issue? What did it finally end up being? I am getting the constant P0300 code as well.

Thanks,
Coffey

 

 

Had issue on 2003 - 200000 miles. Bad wire connectors. Intermittent connection. Wires old and dried out. Bought new harnesses for coil ignition plug and play both sides. Solved no more issue.