long story short, I took my car out to the track and was running very slow. Kind of felt like it was loading up. Hooked up my buddies narrow band air fuel gauge and found that at WOT it was running lean runs ok at partial throttle but under a load or WOT runs lean and some time it will surge @ WOT and then run fine??? with lots of power???
I have replaced the fuel pump, Fuel filter, fuel line all the way don’t know which direction to go in now? Regulator? O2 sens? Any ideas

 

What are you using for a regulator? Has it always done this or did it run fine before and just started acting up? A bit more info on your setup would help also. What engine, heads, cam, injectors, intake, MAF sensor, and engine management?

 

ok its an LS6
fast 90/90
42# injectors
Aeromotive fuel pressure reg
no MAF SD tune
MS3 cam
it never did this befor just started.

 

also has 255 lph fuel pump
- 6 fuel line
ls6 heads
aeromotive fuel rails
new pistons and rings have about 2000 miles on motor

 

Check for leaks - in the intake (unmetered air = lean)

Need a WBO2 - period. If the regulator is adjustable, you may need to do some re-adjusting.

Also, monitoring your O2 sensor performance may indicate if it's time for new ones.

 

sounds like it could be related to o2 sensors or unmetered air from an intake leak. both of those should throw a code. depends on your setup though.