So, I just replaced the water pump on my '98 1500 5.2. Drove it to work today and it seemed to be fine. I had noticed a little power loss before, but attributed that to the plenum gasket which I still need to look at.

However, when I was almost home, I started having other problems. I went into town and after I cranked back up and left the bank, I ran into a problem. When I stepped on the gas from a stop, the truck shuddered real weird and there was *******ly no power. I pulled over and shifted into park and then back and that seemed to fix it. Stopped by AutoZone to pick up my plenum gasket and headed home.

All is fine until about 3 miles from home (this is about 4-5 miles after AutoZone). Suddenly, a real loss of power. At first, I thought maybe the transmission wasn't shifting. I turned O/D off to see if there were any changes. Then I realized. I was hitting close to 3k RPM but was actually losing speed. I slowed down and coaxed her home at about 45 mph, but still at higher RPM than I should have.

My thoughts: cat converter. But, I'm not great at diagnosing, so wanted to see what others thought.

I had a similar loss of power problem back in December, but it seemed to be a fluke as it didn't repeat itself. This one was worse and, for a few minutes, didn't know if I'd make it home.

 

If you read the plenum sticky, you can see that it talks about pulling the front o2 sensor and seeing if it runs better. If it does, your cat is clogged.