Hello, I have a 1999 ram van 2500 that I rebuilt a few thousand miles ago. It has run fine and the other day while I was driving to work it started to loose power on acceleration and going up hill. it got worse and worse and I brought it home. No codes, no heating problem, no odd noises, no oil or water issues, nothing I can find at all. The fuel rail pressure is 49-50psi steady, I removed the valve covers and all the valves look to be functioning fine. I have not done a compression check on the cylinders, but expect solid numbers there. It starts and idles OK, but dogs bad when I try to rev it. It is a throttle body with injectors. It is a 318ci motor. All new parts. I am wondering about the ECU, but as they are expensive, I don't want to throw cash at it. I am at a loss and stumbling over how/what to test further. Any ideas would be greatly appreciated.

 

You could take out the o2 sensor and see if it runs better...you may throw a code, but if it runs better you may have a clogged cat

 

A clogged cat, a bad TPS, or a bad MAP all come to mind.

 

Thank you both, I will try and test these items ASAP and let you know.
Both the diagnosis on the TPS and MAP say that they will throw a code. Since I have no code, I wonder about these, but will do a test anyway.
I considered the clogged cat, but the exhaust seems like it has good flow, but will also try this as I could be wrong.

 

Update:
I tested the TPS and the MAP and they test good. No hesitations and smooth as silk.
So I am thinking, if the cat is clogged, then the O2 sensor will not make a lot of difference being removed as the hole is small. So I unbolted the exhaust from the manifolds and fired it up. Aside from being loud and rich, it seems to rev good and sound solid. So the exhaust is the problem and probably the cat and possibly the muffler as both are older than dirt. BTW I have 365k on the beast so I suppose it's time or maybe time again...
Thanks everyone.