could very well be bad O2 making it run silly rich

also verify the coolant temperature by pointing an IR temp gun at the thermostat housing

 

I think i will try cleaning the cat when i do the exhaust. And i could try that sensor if that fails. But i will poke around with the IR gun before i do that. I belive if the cat in and out temps are different that means its plugged?

 

If you don't know the history of the o2 sensors change them out. I've replaced them on 2 vehicles in the past few weeks. The wife's Blazer had issues similar to what you describe. Change 2 upstreams yesterday and solved the problem. Waiting for the other 2 from Rock Auto.
Here's what you need:
upstream- NTK 23151
downstream- NTK 23099

 

See if you can get that code again and post it here.


And, while you're at it, check for pending codes.


Using a scanner that shows live data you can see the up & down stream O2S activity. If the Cat is bad it will show up.

 

Have you checked the fuel pressure yet?

 

The fuel pressure held at 50 from the prime all the way to higher rpms. And thanks for the part numbers. Im going away this weekend but when i get back i will post the code

 

So today we put the new muffler on and i noticed peices of the honeycomb material from the cat broken off and sitting inside the muffler. And the engine code is "P0138 o2 sensor high voltage bank 1 sensor 2"