My 04 Dakota 4x4 is losing power and sounds like it has a cold, like it's plugged up, but it's not the cats, even had the pipes cut to verify with a visual after the normal diagnostic crap.

164,000 miles
Auto transmission
New fan clutch, plugs, TB cleaned, new TB sensors, no codes, not over heating, all fluids look good.

It has a cat back Magnaflow exhaust on it and instead of hearing the exhaust note behind me, I hear it under the hood and in the cab, it's really down on power...Used to be a snappy little motor, fun to drive..Now it sucks.

???

Not the cats how about the muffler?

I thought about that as I posted up...I'll look because it sure sounds like it's the exhaust side.

Spark Plugs? the OEM 4.7 plugs are copper plugs and give up after about 40k miles.
Scott

Not true at all. Mopar suggests a plug change later than that and I went 140K on the original Champions in my 02 4.7 quad cab.

Check to see if it's the fuel pump, put a gauge on it, been there done that chasing down the "ghost"

I guess your mileage will vary. I bought my truck brand new and at a 40K it was running fine, then one day would not start. Had it towed to the dealer and was informed the plugs were shot. This dealer said that 40k was max for the copper plugs. I swapped to iridium and never had another issue.
Scott

I'd say pull your valve covers and check your timing chains for slack. Mine start running like crap and it was my bottom chain that had jump two teeth along with the guide/shoe being worn causing the chain to flap around on the one side.

I had the same thing happen on my '06 4.7 HO. Pulled the plugs at 40K and 3 of them had the center electrodes burnt out of them. I couldn't believe it still ran.

Sounds like timing chains jumped

Was it a gradual change or a sudden one?