Lifted 1998 Tahoe's steering isn't tight...makes me nervous...

I purchased a 98 Tahoe with a 6" Fabtech lift and 35" tires. I've replaced the front end (upper and lower ball joints, tire rods, brakes, rotors, master cylinder, sway bar end links, steering dampener), lowered the torsion bars, replaced the transfer case, and had an alignment done. The steering wheel clicks once or twice at times during driving/use, and the mechanic said it's the U-joint where the steering column fits into some other thing...I'm not exactly sure. He said it wasn't dangerous. The tires respond well when I turn the wheel, but the truck still drifts, the steering wheel moves and needs constant correction, and the truck pulls to the left slightly when I brake. I am lost and don't know how to make the steering any tighter. Please help! I love my big ol' truck!!