JBsZ06

Got the car tuned. Ran great...then as time goes on it starts to run crappy.

Go visit the tuner he plugs in the hp tuner to the car and reads the file. The car then runs great...and over a period of a week? the car starts to run crappy..

So he suggests I change out the fuel filter.

I change the fuel filter, the regulator (part of vette fuel filter) the maf, the wires, the plugs, the air bridge, the coolant sensor, I seafoam the TB and topend through the pcv hose...I pull the manifold to see whats going on and that there is no air leaks etc...The car has 57K miles on it. The mechanic (not the tuner says) the existing injectors are all at 12.5 and don't need to be changed? I got some very low mileage injectors that I want put on...even though the mechanic saying it doesn't need injectors...but anyway...

The runs good for a week and then the engine starts to degrade in smoothness and performance.. .....

(feels like the engines pulling timing or something...)

Both the mechanic (with tech II ) and tuner say the 02 sensors are fine.
Something about them cycling properly.

Anyone ever run into this? and what was the resolution?

Thanks in advance.

JB