I have a 2001 2500 with 360 and 276'000 km (roughly 171'500 miles) with a 4.10 rear end

Ever since I bought it it has been kinda of a dog. I can still do a break torque but it doesn't have much get up and go or towing power.

As of lateI have been trying to compare to see if I am just imagineing it.
The company I work for has a 2003 dakota with 5.2 that will run laps around my truck. I realise that the dakota is much lighter.

As an RV parts manager I drive many trucks with trailers so i have somewhat of a basis for comparison but sadly have not had another 360 to compare to.

Now I still may be just imagineing this but what do I do next?

Here is what I have done so far.
- New battery
- tune up with 8.5mm wires and new serpentine belt
- many cans of injector cleaner
- complete cooling system flush with new thermostat
-rebuilt transmission (that was for other reasons though)
- changed all fluids (axles, t-case, etc)
- mopar round filter air intake
- other small misc. things.

It warms up like normal and does not throw any codes and it getting normal mileage.

The only other three things i can think of are plenum, death flash and cat.
Or is it just getting to be an old tired engine?

I am starting to think it is the plenum but that seems like such a daunting job...

My next project is a new cat / muffler and new o2 sensors.

I use it for a 70km round trip commute every day and for towing my 5000lb fifth wheel in the summer.

I appreciate any help you guys can provide or ideas you may have!

 

i wouldnt say its old... mine is old. i would do a full tune up on it, plugs, cap and rotor. best way to see if your cat is goin out would be to let it run and see if its glowing orange, that means its clogged. If its on its way out you should hear what sounds like marbels in a can. to check your plenum, open up your throttle body and look down in the intake with a flashlight, if there is oil = new plenum.

i think after all you have listed is done, it should bring your truck back to life

 

my 5.2 was such a pig it couldn't get out of its own way. i think each of these things contributed to making it run a better, but since i did several at once, i can't say for sure which improved most.
Hypertech - a little improvement, but caused severe pinging on 87.
new TPS - huge improvement.
Plenum, Timing Chain, Tune up - big improvement.
big tires and 3.55 are still hurting it.