The house that he lives in is a 3 bed 2 bath house that's approximately 1800-1900 sq. ft. I think it is highly unlikely that ALL the lights are on one circuit. In fact I'm 95% sure they are not. If this is the case, then I have several loose connections in the attic. If the lifts are on different circuits, then what could be causing this.
Joey, a little flicker is normal, but rarely enough to complain about, so let's presume yours is abnormal. A few things:
1. Anything that affects more than one circuit must be either in, or ahead of, the panel. So, that's where you should be checking your voltages first.
2. There are two basic types of flicker:
a. Both line voltages drop, when a 240v load such as central A/C compressor starts.
b. One line voltage drops, other line voltage rises, when a 120v load such as a portable heater starts.
I suggest reading one line-to-neutral voltage while turning on a large 120v load, then reading the other line-to-neutral voltage while turning on the same 120v load in the same outlet. If one rises while the other drops, the issue is somewhere in the service neutral. Let us know how much each of the two voltages change, as well as line-to-line.
You should be able to see your voltages bounce around in sync with the flickering. As long as you see this happening in the panel, you can be sure the issues are on the incoming service conductors, and not within the house wiring. Common culprits are long and/or too-small service drops, poor connections in the meter base, corroded conductors and splices, etc.
Also, you can look for poor connections and breakers by looking for any voltage across a device, between two points that should be effectively tied together. A good fuse or breaker, or a switch that is 'on' should read as a short. If you put one voltmeter probe on one incoming hot, you should read 0.0v to one panel bus and every other breaker load terminal.
In other words, you should read 0v, 240v, 0v, 240v, etc. as you move down each side of the panel. Bottom line is that flicker is the result of voltage drop, which is the result of current through a pathway that has more resistance than it should, either by defect or less-than-ideal design, or something has changed since the service was first installed.
You need to determiner what and why.