carb issues??
It sounds like it's definetly running lean. The Avenger carbs are good carbs but like any carb when it's not adjusted or jetted right will run like crap. Like the others said go back to basics. First adjust the float level then adjust the idle mixture adjustments and then check the accellerator pump to make sure that it is spraying the instance you push the throttle. If all that doesn't cure it it probably needs bigger jets.
A buddy of mine just bought a new avenger for his chevy pickup and even though Holley claims their adjusted close right out of the box their not. We had to raise the float levels on both the front and back alot (about 2 full turns per bowl) and then readjust the idle mixture screws. I also bought one last year and it ran extremely rich in the secondaries. I pulled the bowls off to re-jet it and found they had installed the wrong secondary jets at the factory. It had 88's in a 670 carb!!! There only supposed to be 68's IIRC so it's no wonder it ran so rich.