2 years ago I installed a Holley Street Avenger 670. I know there are plenty of Holley haters out there but has worked well for me so far. One of the final adjustments at install was I increased jet size about 10 each primary and secondary to get rid of a lean surge. Carb has worked extremely well for 2 years. Over the past month I've noticed what feels exactly like the lean surge again. It's so minor my wife can't even tell when it happens but as the driver and being more "in-tune" with the car I can sense it. Basically on a completely level road trying to maintain same speed with only the smallest amount of pedal applied you can feel it. I use enough gas that it has no time to get stale and I use fuel treatment every fill up. Any opinions on why it would change? Do you suggest pulling the jets and cleaning them? I can't imagine I would have to increase jet size more since they worked for 2 years now. Otherwise it is still working great.