2003 tahoe 5.3l running rich... losing power
 

Hi All,

I have a 2003 Tahoe 5.3L Z71... 110k miles on it. I have done tremendous amount of work on my car because all of a sudden my mpg went down from 14 to 11 and i feel a huge lack of power from before.

the main issue is that I dont get any codes... but I have done the following:
new tranny
all O2 sensors new
air filter new
air mass flow new
coolant temp sensor new
spark plugs new
spark plug wires new
all new injectors
Compression test PERFECT
fuel pressure test PERFECT
I cut the cats open and they are perfectly clean

My muffler guy did notice lots of un-burnt fuel in the cat, and he said it is causing back-pressure... that is when I changed the injectors.

but even after changing the injectors, the problem continues...and no codes!!!:confused:

someone please help with any ideas?